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the general conditions obtaining in bodies of water, even lakes (Macan 1970). The definition of these habitats has been based extensively on single collections. The findings of a long continuous study of one place now provide information on which the validity of this step can be examined. There are three other objectives. The collections in Hodson's Tarn were started with a view to discovering the effect of predation by Salmo trutta L. on the community, and continued for comparison with catches on artificial substrata. The outcome of the first experiment was described as soon as predation had been reduced to a low level (Macan 1965a, b, 1966). Confirmation of the conclusions is now provided by the subsequent observations. The work with artificial substrata adds to knowledge about the habits and habitats of certain species. Finally changes in the vegetation and in the corixid fauna during the twenty-one years can be related.

(1) The staphylinid faunas of discrete limestone grassland patches and adjacent blanket peat habitat were studied on two areas of moorland in northern England. Terrestrial and aerial components of the faunas were sampled using pitfall and window traps, respectively. (2) Two-thirds of all species taken on the Moor House National Nature Reserve were capable of flight. Flight occurred throughout the field season, peaking in late spring and at the end of the summer.

The highland and moorland reaches of rivers and streams can usually be divided into riffles, with shallow fast-flowing water, and pools, with deeper slow-flowing water. The invertebrate communities living in such distinct habitats are very different and the biological reasons for this have received considerable attention. Only a limited amount of work, however, has been carried out on the spatial distributions of populations of invertebrates and their relationships to environmental factors within these, or any other relatively more homogeneous stream habitat. Scott (1958) and Ambiuhl (1959) have related the distributions of several species to current speeds, and Egglishaw (1964) showed that, even in what was apparently a fairly uniform stretch of riffle, the quantities of several benthic species at different sites varied greatly and were correlated with the distribution of disintegrating plant detritus. Several studies of the effects of certain factors on the distribution of selected species in experimental conditions have, however, been carried out (see Macan 1963). The sampling difficulties imposed by the non-random distribution of most animals apply to stream riffles in the same way as they do to other habitats. The present paper sets out to explore the spatial distributions of benthic organisms (of length greater than 0 5 mm) and their relationships to certain environmental factors in riffles, as riffles usually make up by far the larger proportion of the areas of fast-flowing streams. Within riffles the greatest weight of invertebrates is found among and under stones, and so most of the observations were made on that habitat. Other habitats in riffles in which invertebrates are found, and on which observations were made, include the algal coverings on the upper surface of stones and clumps of moss.

Areas of Britain at altitudes approaching and above the tree line have a distinctive and reasonably well-known flora but their fauna is not known to the same extent. It was thought that the distribution of Lumbricidae in such an area might be limited and that a knowledge of any limitations would indicate some general requirements of the family and possible differences between species. To this end an investigation was made of the Nature Conservancy Reserve, N.R. 80, Moor House, situated in the northern Pennines approximately 11 miles (17 6 km) south of Alston, Cumberland. The Reserve is adjacent to and south-east of Cross Fell and the source of the River Tees and includes Great Dun, Little Dun and Knock Fells. The bulk of the area lies above 1800 ft (549 m); it has a characteristically cold, wet climate (Manley 1952) and is overlain with peat bog in various stages of decay and regeneration. Mull soils, generally accepted as the typical lumbricid habitat, are rare in extent, being restricted to the banks of streams and occasional limestone outcrops.

Systematic ecological studies on the British spider fauna are still few in number, the more important of these being an account of the spiders of Limestone grassland and oak woodland near Oxford by Duffey (1956, 1962a, b) and Turnbull (1960a) respectively, the spiders of an oak wood in Devon by Gabbutt (1956), those of sand dunes in the Gower Peninsula by Cooke & Cotton (1961), and studies on the activity of spiders in three contrasting lowland habitats by Williams (1962). With the exception of casual collecting, little seems to be known of the spiders inhabiting high moorlands, and the present investigation was undertaken as part of a continuing series of studies on the ecology of the British uplands (see Cragg 1961). This project is being carried out on the Moor House National Nature Reserve (N.R. 80) and involves qualitative and quantitative studies on the distribution and interrelations of the fauna in the wide range of habitats to be found in Pennine moorland. The present paper represents part of the studies on spiders undertaken from 1957 to 1960.

Flotation methods for separating small animals from mineral soils have been described by Ladell (1936), Salt & Hollick (1944), Raw (1955) and Satchell & Nelson (1962). These methods are based on the principle that organic materials float in solutions of specific gravity 1 20, whereas mineral matter sinks. Clearly these methods are not suitable for organic soils of the type encountered by the present writer during studies on the Collembola of peat moorland. The extraction apparatus described in this paper was designed specifically for the extraction of Collembola from peat soils, although it would probably be suitable for other groups of animals.

THis survey of badger sets around Denbigh was made in August 1935 and in a week of December 1935. The area searched is shown on the accompanying map, but I cannot profess to have made an exhaustive search personally over the whole area. The country around Denbigh, outside of the Vale of Clwyd, is hilly, well wooded, and watered by numerous brooks; there is a wide extent of moorland in the upper reaches. The farms are dairy and sheep farms, with little arable land. There are nine wooded estates in the survey area, eight of which employ nine gamekeepers. I have examined 15 occupied sets and 14 deserted sets. A badger's set is generally identified by its large entrance, the smell inside, and the heap of soil, grass and stones outside. It will probably be approached by runs, whilst in the soil around the entrance may be badger hairs. Round about the set may be groups of dung, and occasionally padmarks in any soft mud. The presence of a fox or badger can be tested by placing two upright sticks in the mouth of the set, a little wider apart than the width of a rabbit, or even one stick placed vertically across the hole; the sticks will be pushed aside if a badger comes out, but I have had no experience with a fox. A rabbit burrow is usually smaller, with distinctive smell, but with less excavated soil than a badger set, and often has dung pellets on the threshold. A fox's den in a deserted badger set can be distinguished from the badger's occupied set by its smell and padmarks. Reliable information on other badger sets was obtained from five gamekeepers on whose regular beats four of the sets are, the other two being just outside. In addition to this census, information has been gathered from gamekeepers and others on the damage supposed to be done by badgers and on the food they eat. The dung has been examined for evidence, though some food, such as worms, may be entirely digestible and leave no traces. The supposed damage done by badgers, no matter how imaginary it may be, is of sufficient importance for discussion in this paper, because the survival of the badger depends partly on farmers' and gamekeepers' notions and knowledge.

Male red grouse (Lagopus lagopus scoticus (Lath.)) contest for territory each autumn, and some males are successful while others fail to secure territories. This paper describes experiments undertaken to test whether males which were not occupying territories could become territorial if the established territory owners were removed; that is to say, whether the number of breeding males was being limited simply by the territorial accommodation available or by some deficiency in the unsuccessful birds. Previous research consisted of counts of the grouse on 100-120 ha study areas on heather (Calluna vulgaris L. (Hull)) moorland in north-east Scotland, with more detailed studies of the behaviour of individually marked birds on smaller parts of these areas (Jenkins, Watson & Miller 1963, 1967). Territorial behaviour, courtship and pair formation are described by Watson & Jenkins (1964). The population studies showed that there were many more grouse in autumn, even after the grouse shooting was over, than in the following spring. The behaviour studies showed that grouse populations from October to May consisted of (a) cocks which courted hens and defended territories, plus hens paired with them (territorial birds), and (b) non-territorial birds which did not defend territories, show courtship, pair up, or breed. Classes (a) and (b) both included birds less than 1 year old (called 'young' in this paper) and older birds. On average, 52%0 of the August population later became non-territorial over the autumn and winter and died before the next April-May (Jenkins et al. 1967), whereas both young and old territorial grouse survived the winter well and bred next summer. Consequently we postulated (Jenkins et al. 1967) that possession of territory was essential for breeding, and that territorial behaviour in autumn greatly limited the size of the next spring's breeding stock. These hypotheses were open to the criticism that although territorial behaviour was associated with the population changes, it might not really be preventing the non-territorial grouse from taking territories. The crux was to find if they would take territories and breed when vacant ground was made available. If they did not, the hypotheses would be refuted. One might then explain the presence of non-territorial birds simply by suggesting that they were immature individuals, as in many other species where some individuals do not breed till 2 years old or more.

Following the compilation of lists of the deer populations in the Forestry Commission's areas in England and Wales in I938 and again in 1948 (Taylor, 1939, I948), a number of requests have been made for similar information concerning the State afforestations in Scotland. Accordingly, a survey has this year (I 949) been made by the Commission's Foresters locally in charge of the forests referred to in the appended list with the co-operation of Sir Henry Beresford-Peirse, the Commissioners' Director for Scotland, and the Conservators of Forests and Forest Officers concerned. I am indebted to the technical staff of all grades in Scotland, without whose willing help and interest the list now available could not have been prepared. While in no way intended to represent a record of the present distribution of the various species of deer to be found running wild in Scotland, the list gives an indication of the widespread areas over which the native red and roe deer occur, and of localities in which fallow deer and the exotic Japanese species are present. The small number of State forests to the south of the Highland Line in which no deer have been observed are omitted from the list. As would be expected the usual habitat of the red deer (Cervus elaphus) lies over the extensive mountain and moorland areas of the north and west where the species is often to be found in large numbers. Extensive herds of red deer are also present in parts of Aberdeenshire and in central Scotland, and again in one or two stations in the south, but in reading the survey in regard to red deer it must be borne in mind that the boundaries of some of the Commission's Highland and other forests in Scotland are deerfenced, and, although red deer may not be numerous within these fences, they frequently occur in large congregations over the open terrain round about. Deer fencing (61 ft.) has proved a satisfactory although, as might be expected, not a complete deterrent. It is, of course, impossible to tolerate red deer in any but the smallest of numbers on newly afforested ground, and among young growing plantations. If the industralized areas are excepted, roe deer (Capreolus capreolus) can be regarded almost as ubiquitous throughout the mainland of Scotland. The degree of stocking varies widely with local circumstances but, where covert exists, their numbers are frequently considerable. Roe deer populations tend to increase in almost all localities where extensive afforestations are carried out and, in excesssive numbers, roe can also -be very destructive to young plantations, both by browsing and by the use of young saplings as fraying stocks by the bucks in due season. In these circumstances it is obligatory to take measures to regulate local stockings, but it is safe to say that, given adequate covert in sufficient area, the extermination of this graceful little native deer is, in practice, a matter of impossibility if only on the ground of expense, and consequently it is nowhere attempted. Except where red deer are also present in the neighbourhood it is not the custom of the Commission to deer-fence their forests, consequently the roe have easy access to many areas, a fact that not infrequently leads to difficulties sooner or later because the roe is a rapid breeder, twin births being not at all uncommon. So far as the Forestry Commission's Scottish areas are concerned the only acclimatized species is the Japanese deer (Sika nippon). This deer occurs as far north as Loch Shin and, in small numbers, at two stations in Ross and Cromarty and two in Invernessshire; it also occurs in somewhat greater numbers in the Mull of Kintyre and again 'occasionally' on the borders of Fife and Clackmannanshire. Fallow deer (Dama dama) are present at several widely distributed stations but, with the exception of the Drummond Hill district of Perthshire, are nowhere reported to be strong in numbers. None of the further species which have become acclimatized in parts of England such as the Siberian roe (Capreolus pygargus) and the Chinese muntjac (Muntiacus reevesi) have been observed in or about the State forests in Scotland and no exotic species are reported other than Japanese deer (Sika nippon).

Numerically the nematodes are among the most important elements of the soil fauna. To evaluate their role in the economy of the soil, however, it is necessary to investigate their food relations and to convert the results of numerical sampling into biomass and respiration estimates. The present paper describes an attempt to do this for a British moorland habitat. The study area was an upland moor, the Moor House National Nature Reserve in the north Pennines. Details of this Reserve (Nat. Grid Ref. 35/758329) have been given by Conway (1955) and Cragg (1961) and salient features of the main sampling sites are given in Table 1.

This consists of 112*75 sq. miles. It is defined on the north by the coast from the river Conway to the river Clwyd; on the east and south, to Llanfairtalhairn by the river Elwy, and from Llanfairtalhairn to the bridge over the Conway at Llanrwst by the Abergele-Llanrwst road; on the west the area is bounded by the river Conway. It varies in character, rising from sea-level to a height of 1298 ft., but may very roughly be divided into three regions: the coast, the river valleys and a stretch of moorland, much of which is 1000 ft. or more above sea-level. Geologically the area is made up largely of limestone and shales. While lying for the most part in Denbighshire, very small regions of both Flint and Caernarvonshire are included in the area taken.