Sir P. Egerton on Fossil Fishes from Southern India. 93 



all those figured and described by Agassiz. The principal cusp is conical, rather 

 slender, and pointed. It is more upright and less falcate than usual. The antero- 

 posterior diameter of the tooth is small,, in this respect resembling Corax planus. 

 The character of the marginal armature is peculiar. It is rather notched or crenu- 

 lated than serrate, the subdivisions of the edge being blunt and irregular. The lateral 

 cusp is smooth, and corresponds with its principal in the character of its dentelures. 



Otodus ? marginatus, Eg. — Several of the Indian Squaloids are apparently refer- 

 able to the genus Otodus. Of these, two have some re- 

 semblance to the common Otodus appendiculatus of the chalk 

 formation ; and although the characters of this species, as 

 at present recognised, are wide enough to embrace an ex- 

 tensive variety of forms, yet they are sufficiently defined to 

 exclude the Indian specimens. The larger species, of which 

 I have found four specimens, is remarkable for the rapid 

 increase of the antero-posterior diameter of the shaft as it approaches the base. 

 The latter is thick and massive, with a deep depression on the outer surface. The 

 cone in profile is regularly and distinctly incurved from the apex to the junction 

 with the base. It is narrower than in most specimens of 0. appendiculatus. The 

 outer surface is smooth and rounded ; the inner one is also smooth, and more 

 arched than in any species I am acquainted with. A section, taken one-third 

 distant from the base, would represent the inner face of the tooth as nearly semicir- 

 cular. The cutting edge is sharp, and so distinct as to have the appearance of a 

 border, separated from the remainder of the shaft by a shallow groove. The lateral 

 cusp is large, conical, and sharp, having more resemblance in these respects to this 

 feature in the Odontaspid teeth. The corresponding cusp is broken ; but the frac- 

 ture shows that, in all probability, the tooth was symmetrical. 



Otodus basalis, Eg.- — A tooth sent to England by Mr. Cunliffe has a closer re- 

 semblance to 0. appendiculatus than the species last described. 

 Of the various forms comprehended in this species, one fossil 

 most nearly approximates a tooth from the Maestricht quar- 

 ries. Its peculiar distinctive features are, the larger size of 

 the lateral cusp, the greater breadth and obliquity of the base, 

 and the smaller proportions of the principal cone compared 

 with the other dimensions of the tooth. When viewed in profile, the principal 

 cone is straight and narrow, and the cusp from its inward slope forms an acute 

 angle with the principal cone. Both surfaces are smooth and rounded ; the inner 

 are, as usual, rather more so than the outer. The tooth is shghtly oblique, but 

 not so much so as the Maestricht specimen. As this feature varies according to 

 the position of the tooth on the jaw, it is of little value. 



VOL, VII. SECOND SERIES. O 



