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Show 542 MR. J. W . DAVIS O N A [June 23, PLATE XLVII. Fig. 1. Ehacolepis buccalis, under aspect of head, showing ceratohyal (ch.), epihyal (ep>h.), and branchiostegal rays. [28900 a.] 2. Ditto, tail. [P 1958 a.] 3. Ditto, pelvic bone. [P 1962.] 4. Ehacolepis brama, head, \ nat. size. [15490.] 5. Ehacolepis latus, young individual. [P 1959.] All the specimens are preserved in the British Museum, and the numbers refer to the Register of the Geological Department. Unless otherwise stated, the figures are of the natural size. 5. Note on a Fossil Species of Chlamydoselachus. By JAMES W. DAVIS, F.G.S. &C. (Communicated by Mr. A. SMITH WOODWARD, F.Z.S.) [Received June 7, 1887.] Some years ago a Selachian was obtained by Prof. H. A. Ward, which had been caught off the coast of Japan. It was purchased for the M u s e u m of Comparative Zoology at Harvard College ; and in January 1884 M r . S. Garman, of that Museum, gave a preliminary description of the fish in the 'Bulletin of the Essex Institute,' vol. xvi., in which he recognized it as belonging to a new family and instituted for it the genus Chlamydoselachus. A further contribution was made to 'Science' on February 1st following, in which the body is described as long and slender, compressed and thin towards the tail; five feet in length. The head is broad, slightly convex on the crown ; six gill-openings are present; the nostrils are nearly vertical, with a fold dividing each orifice into two parts; eyes moderately large, without nictitating membrane. The mouth is anterior and very wide ; the teeth are arranged in fifty-one rows of six each across the jaws and are all alike. " Each tooth has three slender, curved, inward-directed cusps, and a broad base, which extends back in a pair of points under the next tooth, thereby securing firmness and preventing reversion." The pectoral fins are described as of moderate size, separated by a distance of twenty-four inches from the ventrals, which, along with the anal and caudal, are large; above the anal there is a small dorsal. Mr. Garman considered that " a certain embryonic appearance in the specimen necessitated a search among the fossils for allied species. Most resemblance was found in the teeth of Cladodus oi the Devonian ; but the cusps were erect instead of reclining, and the enamel was grooved instead of smooth." After the appearance of this notice of the new fish, a considerable amount of correspondence took place in the pages of ' Science,' and diverse opinions were expressed as to the relationship of the genus to extinct forms. Prof. Cope considered that the teeth figured by Mr. Garman " show the animal to be a species of the genus Didymodus ( = Diplodus, Agass.), which has hitherto been supposed to be confined to the Carboniferous and Permian periods ; " and in the ' American Naturalist' of April he |
