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Until recently little has been known about the common, pelagic shark, Pterolamiops longimanus . Data gathered during recent offshore cruises show it to be abundant and widely distributed in the warm waters of the western North Atlantic. It occurs at a wide range of salinities but withdraws from some waters when the temperature gets as low as about 21°C. It is rarely present in water shallower than about 100 fathoms. In a sample of 110 sharks few were over 250 cm in total length, although the maximum size reported in the literature is much longer. Fish and cephalopods are the most frequent food items in white-tip stomachs. White-tips are cautious, persistent, and sluggish in their behaviour. They are responsible for considerable damage to long line caught tuna in the Gulf of Mexico. Geographical sexual segregation is a feature of white-tip life history. Fragmentary data indicate that the mating and pupping season is in the late spring or early summer and that the gestation period is about one year. Females probably first mate at a length of about 200 cm, and probably bear young in alternate years thereafter. The number of pups per litter varies from 2 to 9 with a mean of about 6. Shark suckers ( Remora remora ), pilotfish ( Naucrates ductor ), dolphin ( Coryphaena hippurus ) and a copepod parasite or parasites are common associates of the white-tip.

Eight species of tunas and bonitos are known to occur in the Gulf of Mexico, Caribbean Sea, and adjacent Atlantic waters. Seven of these have been utilized, at least on a small scale, in commercial packs of canned tuna. Gulf and Caribbean catches of some species have been processed for the first time as recently as 1955. The presence of tuna as a widely distributed resource available to longlines was demonstrated by the U. S. Fish and Wildlife Service exploratory fishing vessel Oregon in 1954 and 1955, supporting the views of a few earlier observers that the rare appearance of large numbers of tuna in Gulf and Caribbean offshore waters indicated the existence of a diverse but substantial sub-surface population. Effective exploitation of the resource and the development of a prosperous longline fishery probably depends on many factors, not limited to, but including the development of a stable market at locations convenient to fishermen and rapid extension of our knowledge of the areas and seasons ...

A few species of sharks have jaws structurally effective for crushing hard-shelled prey, but the functions of the jaws and teeth of the remaining species, that is of most kinds of sharks, are restricted to grasping prey or to cutting off pieces of prey to get something of suitable size for swallowing. The grasping function is one which may be performed by any shark; but the type of jaw and dentition apparently most effective and most restricted for this pur? pose is that found in the sand shark, Carcharias taurus, one of the more primitve of existing galeoids. The sand shark has teeth especially adapted for holding. The teeth are long, spike-like, and irregularly spaced and are held permanently in position to function in more than one series. The sand shark has

The anterior commissure, which has been presumed to play a minor role in interhemispheric communication, was tested for the transfer of visual, auditory, and olfactory information in patients with complete sections of the corpus callosum. Four of five patients tested with presumed intact anterior commissures demonstrated interhemispheric transfer of verbal and pictorial stimuli presented visually to a single hemisphere. Evidence was also obtained for auditory and olfactory transfer, although successful interhemispheric communication in all three modalities was not found for any one patient. The data suggest that the human anterior commissure is capable of mediating multisensory, interhemispheric messages of a complex nature and provide evidence of functional plasticity in a phylogenetically early cerebral structure.

Two new species of the squalid shark genus Etmopterus are described from the Caribbean coast of Colombia. Both new species are very small and may represent the smallest known species of sharks. Males and females of the type series (180-212 mm TL) of Etmopterus carteri are sexually mature; Etmopterus perryi males become sexually mature at about 160-175 mm TL and gravid females are found at 190-200 mm TL. A key to the eight Carribbean species is included.

Preliminary psychologic testing was carried out on four patients who had undergone surgical sectioning of a portion or all of the corpus callosum and anterior commissure as a treatment for uncontrollable seizures. Results confirm earlier findings indicating the importance of the forebrain commissures in the interhemispheric exchange of a variety of sensory and motor information, and demonstrate that particular portions of the commissural system are responsible for transferring the information of specific sensory modalities. The patients also showed surprising abilities in performing complex tasks assumed to require integration of information from both hemispheres.

Two roots are described for the glossopharyngeal nerve in Silurus (Berkelbach 1915), in Parasilurus (Atoda 1936), in Wallago (Sinha, doctoral dissertation), and in Mystus (Mithel 1964), whereas there is only 1 such root in Bagarius. The lateral ramus of the vagus and the vagus nerve have separate origins from the brain in Parasilurus. In Wallago and in Mystus, the vagus nerve originates from 2 roots, which unite and then separate into the lateral ramus of the vagus and the common stalk of the branchial and visceral

In recent sawfishes, Pristis (order Batoidei), rostral teeth that are lost are not replaced and those not severely damaged in use increase in size throughout life. Presumably similar conditions pertain to fossil sawfish genera having socket-like attachments for rostral teeth. In recent sawsharks, Pristiophorus and Pliotrema (order Selachii), rostral teeth are replaced if lost and do not increase in size after reaching a functional position. Similarities in tooth development and the process of replacement were observed in recent sawsharks (Selachii) and in the Cretaceous sawfish genus Sclerorhynchus (Batoidei). Also, the pattern of varying length of rostral teeth in adults of recent sawsharks (Selachii), which is explained by the appearance of both new and replacement teeth at intervals during growth, offers a possible explanation for the presence of rostral teeth of various lengths in the Cretaceous ganopristid sawfish Onchopristis numidus (Batoidei).