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Show 1867.] MR. J. Y. JOHNSON ON A N E W SHARK. 713 to any part of its surface is visible; and it is the same with the European species, according to the observations of Eschricht and Reinhardt. The hyoid bone is of the same form as that figured in Cuvier's 'Ossem. Foss.' vol. i. pl. 25. f. 13, being only somewhat larger in the middle, where the two cornua hyoidea are attached. The transverse diameter is 20 inches, and the longitudinal in the middle of one of the two points 7 inches. The cornua have a more curved form than that figured by Cuvier, and are 12 inches long. Finally I should mention, what I omitted before, that in the cranium is a distinct lachrymal bone on each side in the prolongation of the orbit at the fore end, like that in Cuvier's figures (pl. 26), to which is attached the zygomatic bone, as Cuvier figures tbe Rorqual of the Cape of Good Hope (fig. 1 of the same plate). The tympanic bone is persistent and firmly united with the cranium ; and the vomer rather short, not longer than in the same figures of Cuvier, and divided at the fore end by a longitudinal fissure into two parallel lobes 2\ inches in length. 6. Description of a N e w Genus of Spinacidce, founded upon a Shark obtained at Madeira. By J A M E S Y A T E J O H N S O N, C.M.Z.S. The Shark which forms the subject of the present communication is closely allied to those members of the family Spinacidce which constitute the genus Centrophorus; but since it possesses a mesial tooth in the lower jaw it cannot be assigned to that genus, and I therefore propose to found upon it a new genus named MACHEPHILUS. Body elongate, prismatico-triangular in section; head depressed, not distinct from the body ; nostrils on the inferior side of the head ; spout-holes large, furnished with valves, and situate on the upper side of the head above the eyes ; a deep groove at the commissure of the lips. Scutella (scales) stalked. Two dorsal fins, each supported by a strong spine. No anal fin. The teeth of different form in the two jaws; those of the upper jaw consisting of triangular cusps on subquadrate bases; those of the lower jaw composed of cusps on subquadrate bases, the cusps being more and more inclined backwards as the teeth approach the back of the mouth, thus presenting oblique incisorial edges. A mesial tooth, consisting of an upright equilateral cusp on a quadrate base, in the lower jaw. MACHEPHILUS DUMERILLI, f . Of a uniform brownish-grey colour. Head rather broad, depressed, PROC. ZOOL. Soc -1867, No. XLVI. |
