(1) The internal structure of Leptobrama mülleri is described and illustrated. (2) Mainly on the basis of differences in the structure of the dorsal fin and its pterygiophores (Table 1 and Fig. 9), Leptobrama should not be included in the Pempheridae, nor is it related to the family except in a most general way. (3) The genus Leptobrama is placed in the new family, Leptobramidae, with the diagnosis and comparison with other forms (Table 2). (4) Systematically the Leptobramidae may be close to the Carangidae, especially to Chorinemus. The ontogenetical study of Leptobrama and the survery of fossil forms are needed to decide its more exact position.
In connection with the studies of the plankton of the depths, a good collection, of deep-sea fishes from Suruga Bay has been made since 1964 by the research vessel “Tansei-muru” of the Ocean Research Institute, University of Tokyo. Through, courtesy of Prof. Yoshiyuki MATSUE, director of this institute, all the fishes have been passed on to the present writers for taxonomic study prior to the examination of the stomach contents from the ecological viewpoint. The collection comprises most interesting species, and it is thought advisable to report upon them as early as possible in order to expedite further collecting. In the present paper is described a new species representing the whale-fishes, a few members of which have just recently been known to occur in Japanese waters. The writers express their sincere thanks to Prof. MATSUE for the opportunity to examine the remarkable fish collection made by the “Tansei-maru”. Also they wish to thank Japan Society for the Promotion of Science for the partial financial support of this study through a grant from this society as a part of the Japan-U. S. Science Cooperative Program.
1. The nervus olfactorius is well developed, owing to the olfactory lobe being situated close to the cerebrum. It supplies the olfactory rosette by three branches. 2. The nervus opticus enters its orbit through the recess between the pleuro sphenoids. At the decussation the left nerve lies above the right. The nervus oculomotorius and nervus trochlearis come out of the cranium through separate foramina in the pleurosphenoid. The nervus abducens pierces a ridge on the cranial surface of prootic and emerges into the orbit through a tunnel formed by the parasphenoid and prootics. 3. The trigemino-facial complex arises by two roots. The facialis branch of posterior root forms the trigemino-facial complex with the anterior root. The hyo mandibular branch of the posterior root receives ramus communicans from the trigemino-facial complex and forms the hyomandibular trunk. The trigemino-facial complex separates into the supraorbital and infraorbital trunks on emergence from the cranium. 4. The supraorbital trunk runs as the common trunk of the opthalmicus superficialis trigemini and opthalmicus superficialis facialis. The infraorbital trunk separates into the maxillo-buccalis and the mandibularis trigemini. The maxillo-buccalis divides into the maxillaris and buccalis rami beyond the orbit. The mandibularis internus and externus trigemini enter separate canals of the dentary. 5. The ramus mandibularis facialis fuses terminally with the ramus mandibularis internus trigemini. Two rami lateralis accessori arise from the trigemino-facial complex and run along the mid-dorsal and mid-ventral lines of the body. 6. The nervus glossopharyngeus and nervus vagus emerge from the cranium by separate foramina. The pretrematic branch of glossopharyngeus develops an anastomosis with the hyomandibular trunk. The nervus vagus separates into a trunk of the first and second branchialis, another trunk of the third and fourth branchialis and visceralis and the third trunk of the lateralis vagi.
Some cosmopolitan pelagic fishes which are widely distributed in the tropical and subtropical regions have often been occurred in the waters of Hokkaido in recent time. In this paper, two species which have never been recorded or rarely found from Hokkaido were reported.