1867. j MR. J. Y. JOHNSON ON A NEW 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. pi. 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 cra- 

 nium is a distinct lachrymal bone on each side in the prolongation 

 of the orbit at the fore end, like that in Cuvier's figures (pi. 26), to 

 which is attached the zygomatic bone, as Cuvier figures the 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 di- 

 vided at the fore end by a longitudinal fissure into two parallel lobes 

 2| inches in length. 



6. Description of a New Genus of Spinacidce, founded upon 

 a Shark obtained at Madeira. By James Yate Johnson, 

 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 Centi-ophorus ; 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 sup- 

 ported 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 pre- 

 senting oblique incisorial edges. A mesial tooth, consisting of an 

 upright equilateral cusp on a quadrate base, in the lower jaw. 



Machephilus dumerilli, S . 



Of a uniform brownish-grey colour. Head rather broad, depressed, 

 Proc. Zool. Soc — 1867, No. XLVI. 



