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1. The diurnal fluctuation of carbon dioxide content of water in eel-culture-ponds was studied by means of the diffusion analysis method. 2. Total CO2, HCO3- as well as H2CO3 (dissolved gas of carbon dioxide plus free car-bonic acid) were found to decrease in the daytime and to increase in the nighttime. Their minimum figure was observed in the afternoon at the time when O2 was at its maximum, and the maximum one was observed early in the morning at the time when O2 was at its minimum. The fluctuation of CO3- content was contrary to that of other forms. (Fig. 1-3.) 3.The range of the diurnal fluctuation of carbon dioxide content was proportional to the density of phytoplankton, the density of fish, the total amount of solar radiation, and the tem-perature of water. (Table 1.) 4. H2CO3 content of the water ranged from 0.003 to 0.821 mEq./l early in the morning at its maximum. These values were considered not to cause the surfacing of eels which is a sign of dyspnoea. (Table 2.) 5. Total CO2 content of the water ranged from 0.11 to 3.58mEq./l in the afternoon at its minimum. (Table 2.)

In the middle of November, 1964, a total of 13, 094 tagged sea bream, Chrysophrys major TEMMINCK et SCHLEGEL, were released at the 352nd 160th, and 371st official blocks in the Yellow Sea to determine their movement and distribution (Figs. 1, 2 and Table 1). Sixteen hundred and three recoveries were made through March, 1965. Analysing the recovery data, the results obtained are summarizing as follows: 1) The fishing intensity was thought to be very high during the period between November and December in this area, from the fact that 86% of the recoveries were obtained during the first 30 days just after the liberation (Table 2). 2) They moved in all directions within 30 days after liberation, but thereafter, most of them traveled east or southeast toward their wintering area (Figs. 3, 4). 3) The speed of the movement tended to increase and the maximum was seen at about 20 days after the liberation, thereafter, a decrease in their moving speed was noted (Fig. 5).

In the tagging experiment for salmon in the North Pacific, the body length of tagged salmon are being measured both at the time of its tagging and recovery. Then the differences between these body lengths are considered to be the growth in the period of their migration. Assuming that the growth of salmon in the period be expressed as lt=leKt, the value of K (instantaneous growth rate) could be estimated by this formula. (lt; Body length at the time of recovery, l; Body length at the time of tagging, t; Period by number of day). The data used here are the results of tagging experiments carried out in the waters of Aleutian Is. from 1956 to 1958 by U.S. And the calculated growth rate are shown in Table 1. and Figure 1. In this table it is noticiable that 1) the value of K of mature salmon is larger than that of immature, and 2) the K of pink salmon is larger than those of red salmon and chum salmon.

In the present paper, age and growth of yellowfin sole, Limanda aspera (PALLAS), in the Southeastern Bering Sea are estimated with otoliths taken from 978 specimens sampled during the period 1965 to 1966 (Table 1, Fig. 1). The otolith of eyed side is considered to be better for this purpose than that of blind side (Plate). Marginal increments by month (Fig. 3) indicate that an opaque zone on otolith start to form in spring, that is, the translucent zone (so-called ring) is formed once a year during winter months. Growth of otolith (Table 2) appears to be variable by year class, but analysis of variance, using growth index (Table 4), indicates that their annual increments depend, not on the year class characteristics, but mostly on the prevailing environmental conditions for the year (Fig. 7). The relationships between the fork length and the otolith radius (Fig. 4), and the average growth curves in fork length (Table 3, Fig. 6) are estimated by sex as follows; ?? R=0.239FL0.9154 ?? R=0.274FL0.8890 ?? FLi=400.03(1-e-0.1118(i_0.5212)) ?? FLi=438.76(1-e-0.1004(i_0.5591))

The dolphin, Coryphaena hippurus, is one of the important warm water fish that migrate into the adjacent seas of Japan. This species shows the peculiar behaviour and is attracted by clusters of floating algae or bamboo rafts that are prepared for the purpose of artificial shelters. Out of the catch from bamboo raft shelters (“shiira-zuke” fishery), 132 fishes (40-75cm in fork length) were tagged and released during the periods from August to October in 1962 and the same in 1963. The present paper deals with the result obtained from 36 recovered fish up to January 1964. The following are the results summarized: (1) The recovered fish were all fished from beneath the bamboo rafts or clusters of floating algae. (2) The recovery rate was 27.2% in average. The rate for the fish that had been tagged in the thriving month of September was as high as 44% (Table 1). (3) The fish were recovered within an area extending from the East China Sea to the neighbourhood of Noto Peninsula, Japan Sea. Some 67% of the recovered fish were caught within 30 nautical miles inshore; 72% of them were fished within 10 days after released (Table 2, Fig. 1). (4) The dolphin seems to made a northward migration until September and start to move down the south in the later part of that month. A part of population likely tends to the East China Sea through the Tsushima Straits. It is interesting to note that such a high recovery rate in short distance and days-out may be related to the ecological significance and effects of the bamboo rafts to the dolphin.

The dolphin is distributed at a layer from the sea surface to about 15m deep in the fish-ing grounds under report1). Stomach contents taken from the commercial catch comprise two groups of fishes differing in size, juveniles and medium sized ones being about 10-15cm in body length2), The present study covers investigations of materials taken during June through October, 1955-57 (Fig. 1, Table 1). The finding are summarized as follows. 1) Juveniles found in stomachs of the dolphin dominated among the surface net collections. Quantitative species composition of juveniles taken by the fish resembled that in the sea (Table 2, Fig. 2). 2) In most of the stomachs, medium sized fishes exceeded juveniles in amount. Species com-position of medium sized fishes in the stomachs changed two or three times within each of the three fishing seasons (Fig. 3). During such periods of alternation, medium sized fishes decreased while juveniles increased in amount. 3) Based on the above observations, the following inferences have been drawn. The dolphin mainly feed on medium sized fishes but sometimes on juveniles when the former become scarce. Thus frequency of juveniles found in the stomachs is reversely related with abun-dance of medium sized fishes in the sea.

Biological study of Chaetognatha has a considerably long history. Chaetognatha is im-portant macro zooplankton as indicator of water mass, and is considered to be playing an important role as the feed for fish. The present author had an opportunity to go through the Chaetognatha samples collected in the Harima-nada in the eastern part of Seto Inland Sea and in Osaka Bay from April, 1965 to March, 1966. The results obtained are as follows: 1) S. crassa was the most numerous species in the samples, and occurred nearly all through the year with maximum numbers in August. This species was numerically followed by S. enflata which appeared in great numbers in a period from September to December. S. bedoti and S. minima were the species which appeared sparsely in the samples, (See Table 1 and Fig. 2) 2) S. enflata was first seen in the beginning of July in 1965 in the southern part of Osaka Bay, and from that time on this species extended its distribution area northward in the bay. Up to the beginning of September the distribution front reached as far as the center part of the Harima-nada through Akashi Strait. After showing a little more expansion toward December, the population indicated falling tendency in January, and finally disappeared from the area in February. (See Fig. 3) 3) In the Harima-nada and Osaka Bay S. enflata was distributed mainly in the area with transparency of 5 to 10m. and seemed to be densely populated in the area of great transparen-cy. While no specimen was collected in the water mass with its transparency being less than 2m. (See Fig. 5)

Though many biological works have been made on Japanese common squilla, there are few studies on the seasonal abundance, the vertical distribution and the diurnal migration of its alima larvae. The present author studied on this subject in the Seto Inland Sea (Fig. 1) by the year round survey with a fish larval net, 71.5cm in diameter, and obtained the follow-ing results. The larvae occurred during the period from June to October, especially abundantly from June to September (Fig. 2). No larvae larger than 2mm in carapace length were seen in June, while most of the larvae caught in October were 6-10mm (Table 2). The seasonal variation in abundance and in size composition of larvae, with due regard to their incubation period, suggest that the spawning season of squilla in this sea extends from the middle of May to the end of August. Alima larvae exhibit a distinct diurnal migration, rising to the sea surface by night (Table 1). Although this nature is recognized in every developmental stage of the pelagic larva, it seems that the nature is stronger in larger larvae. It may be possible that a larger part of the alima population is distributed just above, or on the sea bottom in the daytime.

Some investigators have already reported that the ratio between the sexual and the asexual individuals, i.e. the cystocarpophytes and tetrasporophytes of Gelidium amansii, is much unbalanced on the natural rocks. From these observations they suggested that the occurrence of the alternation in generations of the life cycle of the present plant may be irregular. According to our investigations on the individuals of the G. amansii having grown on the artificial stone-bed, it was found that the female plants (cystocarpophyte) appear in greater number than the tetrasporophytes during one or two years after settling the bed (33-100%, mean value 64%. Fig. 1 and Table 1), while later they decreased gradually to 20-35% in three or four years after settling the bed, and finally, later than four years, the ratio carposporophyte to tetrasporophyte were about 18 (4-44): 57 (19-86), nearly the same as those on the natural rocks (Tables 1 and 2). Besides, it was also observed that among the new fronds sprouted out on the natural rocks after recovery from the “Isoyake Damage” (desert shore or burned shore) the number of cystocarpophyte and tetrasporophyte are almost equal.

The nitrate nitrogen and the inorganic soluble phosphorus in the water of the rice field culturing the carp have been estimated, (cf. Table 1)., and by the application of the following formula N:P=7.2:I presented by Fleming, the data were analysed (cf. Table. 2). As the result of that, the amounts of N and P which have satisfied the above formula, have sharply dropped at the middle period of August, and this fact agrees with the plankton data presented by prof. D. Inaba. of the Tokyo College of Fisheries (cf. Fig. 1.), so there is little hope for the new production of the carp-diet-plankton after the midtime of August. We, therefore, must feed the carp with some diets or give the fertilizer sometimes earlier. This fact can also be proved from the richness of ash, and protein percentage and poorness of fat percentage analysed on the gotten fish at the end of the experiment (cf. Table. 3).

The scale characters of Pacific Ocean Perch, Sebastodes alutus, and its variations by body regions were investigated for two specimens caught in the Bering Sea in 1965 (Table 1 and Fig. 1). The scale is of a ctenoid type by many characters recognized on the surface of scale (Fig. 2). There are many ridges concentrically around the central plate on the covered portion. The widely spaced ridge zone and the close one appear alternately, and they are considered to be the growth zone and the resting zone respectively (Figs. 2 and 3). The radius of the resting zone, measured from the converged point of grooves to the each outer edge, shows a smooth curve (Fig. 4), but the cumulative number of ridges indicates a inflective line (Fig. 7). The resting zones are supposed to be formed periodically from the Walford's graphic method for their radii (Fig. 6). These characters aforementioned were observed similarly on every scale of the same fish irrespectively of samlping region, and of the shape and the size of scale (Fig. 4, 5, 6 and 7). Therefore, there is a good possibility for determining the age of S. alutus by the scale character, and so far as age determination is concerned, there is no need of strictly defining of scale sampling region.

From middle of May to early August in 1953, survey of surface current was carried out by Salmon Factory Ship with current meter at the west Aleutian and South eastern Kamchatka regions. Observation were made simultaneously at the layer of 25 and 500 meters. Direction and speeds of surface currents were estimated as relative values to those of 500m layer in conception of that no current is present in the layer of 500m. Table 1. shows the result of the observation, and figures 1-8 show water currents relative to distributions of water masses and transparency in every 10 days. As the results of the present research, some presumption given below may be drawn out. In the southern offing of Aleutian Is., the current which flows to south from Bering Sea goes into the water mass which runs northwards, and in this contact zone current moves westerly with velocity of 0.5-1.0 miles per hour. The current that flows to the W or NW with velocity of 2-4 mils per hour exists in the intermediate region of Aleutian Is. and Kamchatka Pen. With above results, we may conclude there are counter currents of Kuroshio in the region of Kamchatka and West Aleutian, and the counter currents flow towards west or northwest. It may be decided that the salmon migrate to Kamchatka from West Aleutian region depending on these currents.

The present paper deals with analysis of length frequency of the young big-eyed tuna caught by pole and line. Especially a relationship between the fishing localities and the discrepancy in the mean length which was evident in the same modal group has been discussed. 1. Data used for the study are the measurement of body length obtained from numbers of samples and the pertaining information furnished by fishing boats at two ports during the period from June to July 1953. 2. In the length frequency two dominant modes, A and B, were recognized not only throughout the samples (Fig. 2) but also in the mean value of each school from 1 to 17 examined nearly in the same period. These findings have led the writers to an assumption that modal group A may from an independent unit different from group B in regard with length frequency. 3. As no uniformity in the length frequency has been found among the samples belonging to the same group (Table 1), correlation between the mean length of the groups and fishing locality has been examined, substituting the size composition sorted by fishing cruise for that by school of fish, because few data on the latter were available for this purpose. As a result it was found that the mean length of the fish in both groups A and B was small in the western area of the fishing grounds and tends to become greater as one goes east (Table 2, Fig. 3). 4. The fact that the survey period fell on the months of June to July when the fish would be migrating northward (Fig. 3) seems to suggest that the easterly increase in the mean length may be attributable to different tendencies of the migrating behavior between the fish in the eastern area and those in the west. In other words, the fish of both groups A and B in the eastern area are supposed generally larger in size than those of the corresponding groups in the west, while all migrating nothward.

Observing the ratio of regenerated scales to the total ones (the apparent regeneration ratio of scales), and the estimated age when the scale had been regenerated, the writer was able to make clear the following facts. The samples dealt with in the present paper were about 263 yellow sea bream caught in the East China Sea, during the term from November 1951 to October 1952. 1. The median value of the apparent regeneraton ratios of scales of each age class increases by about 6 percent per age. The maximum value observed is 76.5 percent, while the minimum one is 0.8 percent. (Table 1, Fig. 2). 2. Polya-Eggenberger type distribution is approximately applied to the frequency distribution of the apparent regeneration ratio of scales in each estimated age stage. No significant difference is observed in this ratio between the north and south areas, sexes, and among ages of samples, regarding 2 and 3 age stages. 3. The ratio of number of samples carrying no regenerated scale to the total number of those shows a relatively high value of 6.8 percent at 0 and 1 age stage, but is less than 3 percent at 2 aged one and older. (Table 2). 4. The average regeneration ratio of scales is 4.5 percent at 0 and 1 age stage, 4.9 percent at 2 aged one and more than 6 percent at 3 aged one and older. (Table 3). 5. Synthesizing above mentioned facts and other ecological and morphological knowledge on the present fish, it will be concluded that the scales of this species fall off more frequently by some physiological causes rather than the mechanical ones.

Though the eggs of sand-eels (Ammodytes personatus GIRARD) have been established as demersal and adhesive ones since INOUE's experiment (1949), the present author have collected them by horizontal haul with a larval net even at sea surface. The eggs are spherical in shape, measuring 0.85-0.95mm in diameter, with a single yellow oil globule. The egg membrane is transparent but usually sticked by minute particles of foreign materials, and the perivitelline space is wide. The newly hatched larva is 4.3mm in total length, with the oil globule in the posterior part of yolk, and with filamentous organs along on each lateral side. (Fig. 1 a-e.) The eggs occurred most abundantly during the period from the end of December to the middle of January, and distributed mainly in areas of rapid tidal current such as the central part of Bisan Seto. As for vertically, the eggs were supposed to distribute more abundantly in the deeper layer. (Fig. 2, Table 1) Those eggs which are adhesive in the laboratory do not always exhibit the same nature in the sea, and there is a possibility that sand-eel eggs may be demersal but non-adhesive in natural circumstances. Under certain circumstances such as shallow water, rapid tidal cur-rent and topographical up-welling, sand-eel eggs are whirled up and distribute even in the surface layer.

The Hyuga Nada (Hyuga High Sea) when taken in wide sense extends off the eastern and east-southern coasts of Kyushu Island, viz., from up north the Bungo Strait down to south the Osumi Penninsula, and abounds, amoungst others, in red gurnards, of which economically important are the following five species; Chelidonichthys kumu, Pachytrigla alata, Lepido-trigla japonicus, L, guntheri and L, microptera. Examination of their stomach contents reveal that they devour by far Crustaceans and those small fishes as hidden in sand-mud or crawling on sea bottom (Table 2). Voracious as they are, their stomach was often found stuffed with food, which weighed 3-4% of the body at maximum. Table 3 and Fig. 1, A-F give the results of the statistical observation of their egg. Ova measuring over 1.0mm in diameter are characterized by having one or three oil globules and almost complete transparency and were taken as mature eggs. The degree of maturity was defined by ratio of mature ova to the whole ovary in weight and is given in Table 6. Single mature ovum weighs about 0.0011gr in Chelidonichthys kumu and about 0.00095gr in Pachytigla alata. Number of ova to be liberated at first spawning is estimated 10, 000-25, 000 in C, kumu, and 2, 000-3, 500 in P, alata.

The biochemical and microbiological properties of bottom muds in a bay or an inland sea may vary owing to the slight differences in layers of muds. In sampling, therefore, it must be given attention to that the layer of muds might be not disturbed, and it should be taken as it is. Using the ordinary sampling-apparatus, the layer of muds is disturbed and it can be hardly taken as it is. Although there is the core-sampler of the apparatus being employed at present, it can be scarcely used, because it is on a very large scale. In this paper, the simple core-sampler fitted for the purpose is designed, and an example of analytical data of the bottom muds taken from Maizuru bay with this apparatus is shown in the Table 1.

Though many works have been made on the habit of sand-eels, there are few studies on the nocturnal behavior of the fish. The present author found following facts in regard to the subject through the survey with the fish larval net (71.5cm. in diameter) in the Seto Inland Sea. During the period from January to May, sand-eels rise to the sea surface by night, and especially abundantly in January and February (Table 1). Those fishes caught in the period up to early in April were all 1-age fish, and those caught thereafter were all 0-age fish (Fig. 2). These fishes, especially in January, were thin after spawning, and the indicator of body length-body weight relation continued to increase in its value during the period (Table 2). From the stomach condition, it was affirmed that they keep on feeding even by night. Adult sand-eels seemed to feed seldom on larvae of the same family, at least by night, on account of the fact that they are swimming in the separate layers of the sea (Table 3).

The distribution of the mackerel-larvae, P. tapeinocephalus was studied at the three sections, at the surface, 10m layer and 20m layer around Osumi Islands; The results obtained are as follows: 1) Mackerel-larvae were collected at the three layers (surface, 10m layer, 20m layer) in the fishing ground and the adjacent sea from February to May (1958, '59) and the water temperature was varying 16.3-22.4°C). 2) The total length of the larvae was within 4.8-11.8mm, and the larvae-size frequency showed almost the same figures through each month. 3) As the Table 2 shows, the collection-rate (collection frequency/net drawing frequency×102) showed highest at the 10m layer, and the seasonal change was hardly observed. The collection-rate in the surface showed high rate in the morning, and it became low in the daytime. And the collection-rate in the 20m layer was somewhat lower than that of 10m layer, and the seasonal change was small. 4) The vertical stability change of the layer from surface to 10m is assumed to have some influences upon the distribution of the larvae in the surface layer.

The ratio of the liver to the whole body in weight of several fishes (Table 2) varied from 1 to 2.5%. Table 1 lists the fat content of the liver, and Table 3 gives hydrogen-ion concentration of the same. The authors obtained vitamin oil from the liver by the pepsin digestion method, and found the optimum of the temperature to be 40°C and that of pH to be 3•4 ?? 3•7 for this procedure. Table 6 tabulates various ingredients of the liver oil thus obtained.

Scales of adult sockeye salmon migrants were collected from 19 rivers along the coasts of the northern Pacific (Fig. 1). These scales were magnified 100 times and the scale character ‘FR’, distance between the nucleus and the last annulus of the fresh water zone along the symmetrical axis, was compared among these fish groups. From the comparisons of the scale character, the characteristic of Bristol Bay's race was established in both cases of 52 and 63 aged fish groups. Therefore, an attempt to estimate the percentage of the Bristol Bay's race of sockeye salmon in the western high sea area of the northern Pacific was done, and the following results were obtained. 1) Age of sockeye salmon caught in the western high sea area of the northern Pacific are 42, 52, 53, 62, 63, 64, 73 and 74. Among such aged fish, 52 and 63 aged ones are most abundant and totals of the fish of these two ages occupy more than 70 percent in every fish group (Table 1). 52 and 63 aged fish groups, therefore, were studied. 2) The mean values of the scale character ‘FR’ of the 52 aged sockeye salmon migrants collected in rivers are ranged from 0.37 to 0.49mm in fish groups of Bristol Bay and from 0.20 to 0.37mm in most fish groups of Asia and other two areas, Gulf of Alaska and America-Canada (Table 2, and Fig. 2, 3). Those of the 63 aged fish are from 0.57 to 0.69mm in fish groups of Bristol Bay and 0.35 to 0.53mm in most fish groups of the other areas. Therefore, the local race, Bristol Bay's one, can be recognized through its scale characteristics in both cases of 52 and 63 aged fish groups. 3) Frequency distributions of the scales character “FR” of groups of 52 aged sockye salmon caught in the western high sea area of the ocean contain some fish groups with larger mean values than 0.37mm, which are the characteristic of the Bristol Bay's race, and fish groups with smaller mean values than 0.37mm, which are the charac-teristics of fish of Asia and other two areas. On the other hand, frequency distributions of the scale character of groups of 63 aged sockeye salmon caught in the high sea are near the coast of Asia contain few fish groups with larger mean values than 0.57mm, which are the characteristic of the Bristol Bay's race, though those of fish groups caught in the mid ocean contain some ones of Bristol Bay's race. 4) Some 52 and few 63 aged sockeye salmon of Bristol Bay's race which appear in the high sea area near the coast of Asia were bred in 1956 and 1955 respectively. Abundance of appearance of the Bristol Bay's race of sockeye salmon in this sea area, therefore, differs by year in relation to abundance of its fry production of each year.

To know condition of Population of the common Shrimp, Palaemon nipponensis is of primary importance in the management of the fisheries, wherefore the present investigation has been done. Two sets of materials available for the present study were taken by a kind of fixed net from 7 localities situated on the west coast of northern part of the lake Kasumigaura. One of which was captured simultaneously on November 29, 1947, the other on June 3, 1948. The distance between both extreme localities of those 7 ones about 11.5Km. Chi-square-tests were made on body-length of samples of those 7 localities. The probalilities led from the test are given in the Table 4. From the table some local groups of the shrimp-population may be seen. Remarkably enough, the localization appears stronger in case of material obtained in November and that of male.

As far as we are aware, none ever described in detail the life-history of fish belonging to Scleroderm in Japan, while the, present fish, one of Scleroderm, is a common commercial as well as game fish in Ise and Mikawa Bay. The present study is summerized as follows : (1) The breeding season covers the duration from June to August. The number of eggs the female possesses is counted by examination of the ripe gonad. The result is shown in Table 1. (2) The egg is pelagic. Artificial fertilization is by no means difficult and gives success-ful result. The larvae and the youngs are described and figured (Text-figures). (3) The yearling grows up to ca. 10 cm in body-lenght at the fall of the year. From that it is clear that the small size group (9-14 cm) observable in the breeding season belongs to the 2nd year class. The age-determination is also made by the study of the vertebral bones. The growth rate is shown in Table 5. (4) The male ripens in smaller size than the female. The biological minimum is 12cm in the male, while it is 15cm in the female, and the former belongs to 2nd year class and the latter to 3rd year class.

The volatile basic-and amine-N of the fish sold at the store in Sendai, August 1957, were determined by Conway's microdiffusion method and the results obtained were summarized in Table 1. Comparing the values with those in fish of May and June 1957, the quality of marketing fish was better in summer (26-35°C) than in spring (18-25°C) (Table 1-3). This fact will be caused by the rapid transportation from the fishing ground to the fish store and the proper treatment of fish with ice in August. It was found that the percentage of fish of the poor quality was small in the well equipped store (Table 5) and that comparing the bottom fish with the surface fish, the former always had the high value of the volatile amine-N in comparing with the volatile basic-N (Table 1, 6).

The behaviour of skipjack shoals has often been studied since many years ago on the basis of the data of angle fishery. As regards seine fishery data, in turn, they have also become available recently for skipjack and tuna made a rapid progress on the coast of the north eastern sea areas of Japan. Therefore, in this paper, the relation of behaviours of skipjack and tuna to their catch and also the relation of grouping of fish in shoals to their catch were studied from the data of seine fishery. The difference in catching power was also pursued between one boat seine and two boats seine. The species of fish treated in this paper are blue-fin-tuna, young-tuna, yellow-fin-tuna, sword-fish, skipjack and their mixed shoal. 1) The values of the catching ratio (ƒ) and catch (c), which were calculated for three ranks of grouping, namely, Great-, intermediate-, and small shoals, and for various species of shoals are indicated in Table 4. Showing this table, the values of ƒ of small shoals in various species are higher than those of large shoals. 2) The type of shoals has been sorted into nine classes from the viewpoint of their characteristic behaviours as described in Table 5. The typle corresponding to good catching ratio was found one of the so-called “shoal with baits” indifferent of species to shoals and this finding forms a contrast against the case of angle fishery. 3) There was found a little difference in catch per hauling between one boat seine and two boats seine.

Research has been conducted in regard to the horizontal distribution of catch which is likely influenced by the seam joining two unit of net adjacent to each other. The data derived from drift nets operated for sardine, Sardinia melanostica, in the Japan Sea. The examined results through the method of analysis shown as an example in Table 1 are mentioned in the following. The spreading motion of distribution of catch over the net would be disturbed in some degree at places of the seam if fishing is operated at day time, but not at night (Table 3). This tendency is further accentuated if two sides of net boarded by the seam are different in colour or in luminosity (Table 5).

This paper describes the results of comparative experiments on the pulling power of a large stern trawler (3400 gross ton 4000ps, made in Japan in 1967) which operated at a rough sea and calm one. Table 1 shows the specifications of the trawler used for the experiments, Table 2 shows the specifications of trawl gear and Fig. 1 the tension meter. Table 3 and Fig. 2 give the results of the experiments. According to Fig. 2 the relation between the shaft horse power (B. H. P) during towing and the pulling power (E. H. P) measured at the calm sea (Beaufort 2) is approximated by: E. H. P=0.3 (B. H. P) Through the experiments it has been established that in case the trawler heads wind at the rough sea the pulling power decreases by 40-50% as compared with that at the calm sea, but on the contrary it increases by 15-20% when the trawler heads leeward.

Succeeding to the previous papers, the present paper deals with the presence of Cd113m. Group II, separated directly from the raw ashes of the liver or the pyloric caeca of skipjacks, Katsuwonus pelamis, or from the radio active fration, “6-L-F2”, obtained by ion-exchange resin, was fractionated further into each member (Fig. 1). The considerable activity was found in Cd-fraction in both cases (Table 1). The Cd-fraction showed no decay in 50 days and no γ-ray emission. The maximum energy was found to be 0. 6 MeV., when calculated from the absorption curve (Fig. 2). From these results, the nuclide in question was identified as Cd113m. The weak activity was also found in Sn-fraction in the above fractionation, but the nuclide has not yet been identified.

As far as the adult fish of yellowtail, Seriola quinqueradiata, are concerned, tagging experiments have been successfully conducted to prove a distinct habitude of their migration along the coastal waters off Japan. However, the amount of data previously obtained from tagging the young yellowtail has been insufficient to elucidate their migratory habit. Therefore, the author liberated 160 individuals of the young fish with a tag along the Japan Sea coast of Shimane Prefecture. At the time of liberation in May 1958 and June 1959, they were possibly about two years old with the fork length ranging from 36 to 45cm. (Fig. 1). Analytical studies of the fish recovered by October 1, 1960 revealed the following information. 1) The number of the recovered individuals was 34, constituting 22 per cent of the total released. Among the recovered fish those which stayed in the sea for three to nine months after liberation represented 53 per cent, and those staying out over nine months were 32 per cent (Table 1). Therefore, the present experiments may be said to have produced a richer result than some of previous ones. 2) Assuming that an area within a radius 30 miles from a releasing point belonged to a body of a homogeneous water, most of the recoveries were made in that area (Table 2, Figs. 2 and 3). The fact suggests that the young yellowtail have a rather limited range for their movement. 3) They were recaptured almost throughout the year either in a bay, a shallow water or on a reef within five miles off the shore. 4) Although the migratory habitude seems dependent upon topography of a liberating area, it is interesting to note that those released from the Oki Islands appear to have migrated round the islands once or twice a year in conformity with the coastal currents in the area (Fig. 3). 5) The recovered fish had the body weight ranging from 0.8 to 2.0kg. and the body length up to 50cm. On the basis of a previous study none of them could be regarded as older than three years.

In order to clarify the relation between the driftwood and the boring and sessile animals and the route of the driftwood, etc., the authors had made a series of marking experiments, releasing the experimental driftwoods of lauan (Fig. 1) in the area southeast of Formosa and in the eastern waters of Mariana Islands. The experimental driftwoods were recovered about 5% (Table 1, Fig.2). As compared with the natural driftwoods, the driftwoods recovered showed a remarkable difference in the appearance (Fig. 3). The fishermens who recovered the experimental driftwwods reported that those woods were not followed by skipjack and tunas at the time of the recovery on the sea. On the experimental driftwoods recovered in this experiment, the predominance of Teredora aurita which had developed on the natural driftwoods that were followed by skipjack and tunas could not be found, perhaps because the drifting period of the experimental driftwoods was too short. Further on the experimental driftwoods which had been set on the Izu coast for comparison, Lepas anserifera of big shell, Amphipoda sp., and Balanus tintinnabulum which were seen in plenty on the natural driftwoods could not be founn. Accordingly further studies on the mechanism alluring skipjack and tunas to a driftwood are necessary. To release the experimental driftwoods in more southern seas than the adjacent waters of Formosa and to research the environment of the places where many driftwoods gather by wind or sea current seem also to be necessary.

The result, concerning the dominant or characteristic association of the benthos, in the five regions of the East China Sea and the Yellow Sea, is shown in Table ? and Fig. 1. The relation between the good fishing ground of every valuable fish and the characters of benthos in five region is reported in this paper. The benthos of A region is occupied by Holothurioidca, Macrura, Brachyura, and white or Yellow croacker-especially bottom fish fauna. As for dominant and characteristic group, the following relation was found:-Ophiuroidea to Yellow croacker in B region; Asteroidea, Gastropoda to ribbon fish and yellow sea bream in C region; Cephaloda and Tetraxonida to lizard fish and gurnard in D region; Asteroidea to Black croacker in E region. These valuable fish coincide with the majority of benthos in the superior fishing grounds, but the relation between the food habit of fish and benthic quality is unknown; the result of researches for the environmental factors managed by the majority of benthos was that oceanic current has a considerable influence upon them.

On the yellowfin tuna distributed in the tropical and subtropical zones of the Pacific, we made a biometrical analysis on the various morphological characters, so as to know that the fins Japanese tuna fleets are catching belong either to one population or not, based upon the specimens from 1953 to date. Samples used in this report are tabulated in Table 1, showing the origin, fishing date, number of fish, range and average of body length. All specimens were measured by the junior author at the Tokyo Central Fish Market. Measurements were made in millimeters using slide calipers and a pair of dividers in accordance with the techniques described by Marr and Schaefer (1949). Several samples of yellowfin tuna, Neothunnus macropterus, from the Equaforial Pacific ranging from 130° W to 130° E were compared on sixteen different body characters (Fig. 1) and the following results were obtained. 1) The specimens of yellowfin taken from the same area in different years show difference in maxillary length, anal length and spread caudal (Table 2). But generally we can say with certainty, they have considerably similar morphometrical characteristics. 2) It appears to be a much greater degree of separation between 170° W and 150° E and between 160° W and 130° W, than between 150° E and 130° E and between 170° W and 160° W (Table 3). 3) The specimens of yellowfin from the area of 160°W have shorter head, more anteriorly positioned ventral and pectoral fin than those form the eastward and westward regions (Table 4, Fig. 2). But for eye diameter, second dorsal and anal length, the measurement is the greatest in the Western Pacific ones and the least in the Eastern Pacific ones, and this tendency agrees with Royce's result (1953). 4) By the facts above mentioned, it is morphometrically probable that there would be at least three populations rather independently but with some mixing between each other.

A number of the top-shell were put in a bamboo basket and kept folating in a littoral pond (Fig.1) excavated in the rock. They were exclusively fed on the alga, Eisenia bicyclis, and found growing slower (Fig. 2, solid circles) than those living outside the pond (same, squares). Remarkably enough, the spines on the shell were suppressed in growth when transferred into the pond (Fig. 3). The observations on the water-samples taken inside and outside the pond (Table 4) and an analysis of the already published data by previous writers (Table 5) showed that inferiority of the water especially in specific gravity, alkaline reserve, contents of Cl and K was mostly responsible for the changes.

In order to know the setting season and the growth of Tapes japonica in their young stage, the author has collected this species over the period 1952 to 1955, at four localities in the Sea of Ariake (Table 1, Fig. 1). The results obtained are summarized as follows : 1) The major periods of the setting are twice a year. One is in May and the other is from the end of November to early December, but the setting in the former season is unstable (Table 2, Fig. 2). 2) The density of setting in December reaches above half a million per one square meter. The young clams set in this season maintain the resources of this species, though those deposited in spring seem to be extinct (Table 2). 3) The growth curve of the young clam which sets in November and December has several changing points in its growth rate. The shell length on the coast of Saga Prefecture in the Sea of Ariake, reaches 1mm. four months after setting (early April), 10mm. after six months, and 27mm. after a year (Figs. 3, 4).

In the present paper, growth pattern and age composition of the sea bream, Chrysophrys major, are estimated by scale length and fork length of the fish. During the period from April 1958 to September 1959, 1010 specimens caught in Wakasa Bay were examined in the Nishi Maizuru Fish Market, Kyoto Prefecture. They were measured in the fork length, body depth, head length, body weight and on the scales. In this case the scales were collected from the mid part of the body, namely the 5th and 6th scales in the vertical line downwards from the 13-15th lateral line scales. Scale length and each annual ring size were measured along the line from the focus to the basilateral angles. The results obtained are the following. 1. The monthly change of growth rate of marginal region (α) on scale with 1-5 annual rings (under 5 years old) of the fish were examined so as to conjecture the month when the annual ring was formed. Succesive collections of the scales throughout the year have led the writer to believe that scale annual ring is formed in the spring, from March to May (Fig. 2). 2. Average actual annual ring sizes (rn, γn+1) of the scale are plotted against each age in accordance with Walford's growth transformation (Fig. 3). Each point is so well distributed on two lines that these meat at the 6th point. 3. Estimated annual ring size is given from the result of the Walford's growth transfor-mation (Table 1). Fig. 4 shows the relation between fork length (L in mm) and scale length (R in mm). The relation formula is as follows: L=34.2+16.5R+1.7R2. 4. In Table 1, estimated fork length at the time when each annual ring of scale was just formed is obtained by application of the estimated annual ring size of each age to the relation formula. Although results obtained present slightly lower rate, they agree in general with the average actual fork length on the whole, especially whithin the first dozen years or so. Compared with the sea bream of the Inland Sea of Japan, it seemed to me that the sea bream of Wakasa Bay has inferior growth rate about one year in early stage (from 1 to about 7 years old) and two or three years in older age.

Three closed-circulating systems for carp culture were constructed by applying the standard design reported in the preceeding paper1). Each of these has 25, 48 and 76m2 of filter bed and 75, 135 and 360m3/h circulating pumps as shown in Table 1. Carp culture tests were carried out six times in the period from 1961 to 19642, 3) Into the systems 0.55-3.00 tons carp were introduced at the beginning of the tests and 0.6-4.0 tons of dried silk worm pupae and dry pellets were given in about two months (Table 2). The percent increase of body weight was 60-80%. The utility ratio of feed was 49-99% (Table 4). Water was supplied during the tests to replace the loss due to evaporation and washing the filter beds. The mean daily supply was 8.6% of the total volume of the water of the system (Table 5). In the 2nd system the total water used for producing one ton carp was 646m3. The increase of some components in the water with 100kg of dried feed were as follows in the 2nd test: Nitrate-N, 2.2kg; Sulphate, 3.1kg; Ca, 2.4kg; K, 0.27kg; Na, 0.15; Mg, 0.13kg; Phosphate-P, 0.07kg, where the value of Ca includes the amount derived by the dissolution of concrete walls. Typical acidification and nitrate accumlation in the water were observed as shown in Table 6. The content of dissolved oxygen in the water was maintained between 4.6 and 2.5ml/l. The balance of oxygen gas and the cycle of nitrogenous compounds in the system were studied (Table 8, 9). The load of the filter expressed in Kjeldhal-N was 74-91g/m3, day, which was higher than that of high rate trickling filter4). From the results of the present tests the elements for designing 1 ton carp culture system were summarized as follows. Fish pond area, 30m2; filter bed area, 12m2; volume of filter bed, 7m3; circulating rate (three times of aseration by water-fall), 30m3/h.

The area of the Kuroshio current or the North Pacific current is known as the quite excellent fishing ground of the Albacore. Albacore in this ground migrates southward during Autumn and early Spring, and is mainly caught by long-line. From Spring to Summer it migrates northward and is caught by rod and line with live bait. As to the former catch the author already reported it's size-composition1). In the present, the author reports the analysis of the size-composition of the latter. The principal informations obtained by this work are as follows. (1) Though the range of the size is confined within the limit between 50 to 100cm during the seasons of 1951 and 1954, there are the remarkable annual fluctuations. (2) The number of length-groups are not fixed by the seasons. 3 or 5 length-groups appear in each season from 1951 to 1954. (3) The modal length of each length-group shows remarkable annual fluctuation. (Table 1) (4) The relative abundance of each length-group is very unstable as shown in Table 2. In most cases, the most dominant length-group occupies the overwhelming proportion. Such a size-composition of the northward migrating Albacore differs from that of southward migrating one as follows. (1) Such advanced age groups* as seen in the sout ?? ward migrating fishes do not appear in these which migrate northward. (2) Size-composition of the northward migrating ones shows the remarkable annual fluctuation, therefore it is able to say that it is much more unstable than that of the southward migrating. (3) The dispersion of the length frequency of the northward migrating ones is much more small than that of the southward migrating ones. Then differences between the two groups seen to be based on ecological differences of them other than the difference of fishing method. In spite of these differences, the author hypothesized that there will be some relations between these two groups on a basis that the body-length of the most dominant size-groups are less than 100cm in both migrating groups. * Age is not determined, larger than 90cm.1)

With a view to propagating the spiny lobster, Panulirus japonicus, several measures have been successfully put into force in the Wakayama Prefecture with cooperation of 29 fishery guilds there. But as to biology of the animal there remain many points to be made out. The biological minimum size of th species in the Wakayama Prefecture was determined by the present author to be 150-160cm in length, morphology of the pleopods being used as a critelion to distinguish adult from immature (Fig. 1). Tagged 163 specimens, 66-206cm long, were riberated and seven were recaptured about five months afterwards. Of these seven, five retained the tag (C. von Bonde's tag) in a perfect condition, and their rate of growth was determined as shown in Table 1.

The patches of the common medusa, Aurelia aurita LAMARCK, have often been drawn into the intake-tunnel of thermal power stations using huge volumes of sea water for condenser cooling. This has created serious trouble in sea water intake. To obtain some basic knowledge for the planning of countermeasures, distribution of the patches was investigated three times by ship in the north-east region of Tokyo Bay, where there are several power stations on the coast. Tracks and stations of these surveys in which one was aerial observation from helicopter are shown in Fig. 1. When patches were found, their characteristics were examined: area and shape were estimated by observation, density was obtained by horizontal towing of a net with an opening 100cm in diameter and with 8.0mm mesh-openings, and biomass was calculated from density and mean diameter of the bells using the relation as shown in Fig. 5. Results of these examinations are shown in Table 2. As for the relation between oceanographic structure and distribution of Aurelia patches, chlorinity distribution presented a fine relation in each surveys as seen in Fig. 2-4. Result of the 1st survey showed that patches have surrounded a low chlorinity line, the contour of 16.00‰ (Fig. 2). Results of 2nd and 3rd surveys are shown in Fig. 3 and Fig. 4 respectively, in which patches were situated near the projecting points of high chlorinity lines. These results suggest that the patches have drifted with the off-shore current of high chlorinity. Results of two vertical towings of patches showed the change of density as seen in Fig. 6 and Fig. 7.

To investigate the strength of the netting twines (see Table 1) against a single blow, the present study was carried out using the apparatus as shown in Figure 1. In such impact tests, an impulsive force is usually applied to the netting twine horizontally. However for this experiment, the implusive force was applied to the netting twine vertically using several cutting steel-pieces (Figure 2 and Table 2). Various observed and calculated values are indicated in Table 3. Irrespective of the magnitude of the exerted impulsive force, the test-piece needed a constant energy necessary for the fracture (Fig. 4), but the required energy varied only in the test-piece lengths (Fig. 5). It seems that the stronger and unexpandable the netting twine is, the more energy is needed for fracture (Table 4 and Fig. 6).

1) In order to estimate the total number of ark shells Scapharca broughtoni (SCHRENCK) living in a limited area and to clarify catching efficiency of this species caught by ark shell dredge, towing experiments were made in a rectangular test area, 600m×10m, in southern Omura Bay, Nagasaki Pref., Japan (Fig. 1). The test area was 10m in depth with a muddy bottom. In addition to the native ark shell population, a total of 4, 950 individuals of marked shell obtained from the same bay one day before were released. From June 16 to 17, 1965, one week after releasing, two dredges were towed simultaneously from a boat (1.1 tons, 6 p. s.) at an average speed of 80cm/sec. Thirty tows were made altogether. Specifications of the iron dredge used in the present study are as follows: i) The entrance flame, 125cm in width and 27cm in height, furnishes with 22 hooks. The hook is 32cm in length and the aperture between hooks is 4.5cm. ii) The mesh size of nylon collecting bag attached to the flame is 6cm (Fig. 2). 2) The results of towing experiments are summarized in Table 1. At first, the total number of native ark shells in the test area was estimated at 2, 388 (Fig. 3). Then the accuracy of this method was tested by estimating the number of marked shells released. The figure obtained (4, 969) coincided fairly well with that actually released (4, 950), indicating the reliability of the method. 3) Applying the estimated total number of native ark shell in the area, the catching efficiency for each towing was calculated both for native and marked shells (Table 2). The catching efficiency of the present dredge was estimated as 0.138±0.055 at a confidence level of 95 per cent.

No correlation was found to exist between the catch and the air-temperature or the amount of rain, although a significant positive correlation was observed to occur between the catch and the amount of snow in the fishing season (November-December) as shown in table 1. The catch is influenced by the conditions of wind ; northerly wind (NNE-NNW) and westerly one (WSW-WNW) at Wazima, Niigata, Akita and Aikawa give bad effect to the catch (Fig. 3), and on the contrary, east wind at Aikawa and Akita and south wind at Wazima and Niigata throw good condition to the catch (Fig. 2, C). The velocity of wind at Niigata causes much effect on the catch, strong wind (7m/sec. and above) being unfavourable for the catch (Table 2).

The distribution of the mackerel-larvae, P. tapeinocephalus was studied at the three sections, at the surface, 10m layer and 20m layer around Osumi Islands; The results obtained are as follows: 1) Mackerel-larvae were collected at the three layers (surface, 10m layer, 20m layer) in the fishing ground and the adjacent sea from February to May (1958, '59) and the water temperature was varying 16.3-22.4°C). 2) The total length of the larvae was within 4.8-11.8mm, and the larvae-size frequency showed almost the same figures through each month. 3) As the Table 2 shows, the collection-rate (collection frequency/net drawing frequency×102) showed highest at the 10m layer, and the seasonal change was hardly observed. The collection-rate in the surface showed high rate in the morning, and it became low in the daytime. And the collection-rate in the 20m layer was somewhat lower than that of 10m layer, and the seasonal change was small. 4) The vertical stability change of the layer from surface to 10m is assumed to have some influences upon the distribution of the larvae in the surface layer.

I studied the bottom fauna to decide the worth of fishing in three irrigation ponds (Table 1) in Tiisagata-Gun, Nagano-Ken. The results were shown as follows: (1) The production of bottom fauna were maximum in O-ike, and minimum in Asama-ike. (2) The degree of apparition and the rate of organization were large quantity on Chironomus plumosus in O-ike, Tubifex in Shin-ike, Corethra in Asama-ike. (3) The cause which control the life of bottom fauna were mostly based on the quantity of dissolved oxygen quantity in water of bottom, and on the nature of bottom matter. (4) On the view of bottom fauna, O-ike and Shin-ike are worth for fishing.

On the Dosigawa, tributary to the river Sagami, dainm and waterway were constructed in 1953 (Fig. 1), and the change of discharge occured (Fig. 2, Table 5). The type of river bed chartged (Figs. 3, 4; Table 6, 7) also, and the change involved that of fishing efforts of Ayu, Plecoglossus altivelis T. et S., fisheries in rapids per day (Table 8). Table 3 shows clearly that fishing methods are highly restricted to the types of river beds. Table 4 explains that most of fishing efforts are observed in rapids especially in the case of fishermen belonging too cooperative. Data under unfavorable condition (Table 2) were eliminated, and EbSj, the density of fishing effort were measured in various subregions owing to procedure described bellow: EbSj=m−k=1n−i=1 EbikSj/m−k=1n−i=1lbikSj where symbol EbikSj denotes efforts of fishing on some fishing ground (i) which has any types of river beds (b), at any creelcensus day (K), in any subregion (S), in any year (j). Symbol lbikSj denotes length expressed in units of 100m. under the same terminology as mentioned above. Following above procedure, the results shown in Table 8 were rearranged into as Table 9. Without considering the coefficient of variation shown in Table 11 and corrective coefficient (Table 1), it may be probably -true that under these prediction EbSj may attain 0.5-0.4 and the yearly change of total efforts was brought force from that of total length of rapids.

Hijikia fusiforme is an edible fucaceous alga, growing in tidal zone in Japan. It sheds eggs periodically at the intervals of seven to eight days (cf. Table 1), from the end of May (water temp. 19°-20°) to early July at Misaki, Kanagawa Prefecture. Shedding occurs in a flood tide of day-time. About 105 eggs are shed from a female plant in a season. As was reported (Tahara, 1929), each egg is enclosed in a gelatinous coat, the latter of which is attached to the mother plant by a stalk. Under this condition the egg is fertilized and develops to an embryo. In the author's observation, about 24 hours after the shedding, the coat dissolves and the embryo is liberated into the sea water (cf. Fig. 1 and Table 2). In laboratory experiment, when the sea water containing the liberated embryos is taken on a glass plate, and the water is carefully run off, so as to assure a contact between the embryos and the plate, many embryos are found fixed in one minute. If the embryos are left with an ample sea water, most of them remain unfixed after five minutes (cf. Table 3). The fixing ability is the strongest just after the liberation. Therefore it is right to suppose that, in nature, the embryos will fix themselves to rock surfaces on the following day of the shedding, and they may accomplish it within one minute, especially on the rocks which are washed by waves at flood tide.

The method to pump up ayu fish (Plecoglossus altivelis T & S) from beneath dam to upper stream of a river was tested. Also, the reactions of the fish to various acoustic noises and to several colored boards were observed. The results obtained are summarized as follows: 1) It was found that ayu fish can be pumped up by fish pump from beneath dam to upper stream of a river (Figs. 1, 2, and table 1). 2) The fish was stimulated by the under water noises of low frequency, and it is suggested that the pumping efficiency could be increased by using these acoustic noises (Tables 2, 3, and Fig. 4).

Succeeding the life history study in the previous paper of three ecological types of “Rhinogobius similis”, the morphological characters of adult fish are compared in the present paper. In spite of the apparent similarities in the body form, the fluvial type is clearly different from the other two types (the amphidromous and lacustrine types) in the colour pattern on the body side (Fig. 1), and in the number of vertebrae, pectoral and first dorsal fin rays (Table 1; Fig. 2). Considering the more distinctive features in the size and number of mature eggs, in the size and developmental stage of newly hatched larvae as reported in the previous paper, it seems appropriate to conclude that the fluvial type is to be referred to the genus Tukugobius HERRE, 1927 instead of the genus Rhinogobius. The other two types, i. e., amphidromous and lacustrine types have no more distinctions with each other than intraspecific variations (Table 1; Figs. 2 and 3). Thus, the fluvial type is named as Tukugobius flumineus and the other two types retain the customary name Rhinogobius similis GILL.

Many springs and flowing wells are distributed in northern vicinity of Odawara. City, Kanagawa Prefecture. Throughout the four seasons, clear ground water is continually flowing out of every well and spring, supplying for domestic and industrial ?? urpose. Although the waters of this district are considered to be of good quality in their chemical properties, curious to say, fishes can hardly be kept alive in these waters. Fishes, when put into these waters just flowed out, soon fall in an unhealthy condition and can not survive long. Gas contents were examined. Sufficient quantity of oxygen for the life of fish was proved to be dissolved in these waters, but nitrogen gas contents indicated abnormally high supersaturations. After some experiments, we reached to the conclusion that the death of fishes in these waters must have been brought about by so-called “gas-disease” caused by the abnormally high supersatuation of the nitrogen dissolved in the ground water. Experiments also teach us that the supersaturation values of the nitrogen above 130% in the water are fatal to fishes. The gas-disease of fish is considered pathologically to be similar to the caison-disease and the diver-disease of man and give us many interesting and important problems for scientific investigation both from theoretical and applied point of view. EGUSA. one of the authors, is now studying the subjects and the results of which will be reported in near future. In this report we will confine ourselves in the quantitative determination of the nitrogen gas in the flowing water of the distict. The summary is as follows: 1.) The flowing water of all of the fifteen artesian wells and two springs we visited and investigated showed the supersaturation of nitrogen gas. The values obtained ranged from 118 to 159%, but were mostly above 140% (Fig. 1. and Table 1.). 2.) It was observed that each well and spring has its specific supersaturation values of nitrogen stationary for a long period. The oxygen contents showed greater fluctuations compared with those of nitrogen (Table 3, 4 and 5.). 3.) Two artesian wells, the waters of which were also known to induce the gas-disease upon fishes, were found in other districts and their waters were investigated. Both wells showed very high supersturations of nitrogen (146 and 161%), but very low values of dissolved oxygen (below 10%) (Table 2.).

A limnological survey was carried on by the writer in the following lakes of South Sakhalin in the summer of 1934; Tibesani-taiko, Tibesani-syoko, Waai-ko and Horahune-ko on the coast of Aniwa-wan (Aniva Bay), and Tyatya-numa, Bakko-numa and Raitisi-ko on the west coast. The morpbometrical data of these lakes are given in tables 1 and 8, the temperature and pH in table 2, and the chemical properties of the lake water in table 7. Tibesani-taiko (table 3), Tibesani-syoko (table 4) and Horahune-ko (table 6) belong to eutrophic Corethra plumosus type with Einfeldia, and Waai-ko (table 5) to mesotrophic Einfeldia type. Raitisi-ko (table 10) is a brackish water lake and Macoma baltica, an eurythermal and euryhaline clam, is very common. There were collected many interesting animals which are new to Japanese fauna, e g. Kamaka kuthae, Piscicola geometra, Cristatella mucedo (statoblasts only), Limnochares holosericea, Thyas oblongata, Forelia ligulifera, Nereis alinensis OKUDA and Valvata pulchella saghalinensis MIYADI. All of them are recorded from Europe or Siberia, except the last two which are new to science.