388 [April 17, 



base is partially concealed by the matrix ; but it appears to have 

 been furcate, and of rather small size. 



Odontaspis constrictus Eg. — A very large proportion of the 

 Indian odontolites belong to the species now under 

 consideration. Out of some dozen of specimens I |i n 

 have not, however, found one having the base suf- " ' ^ 

 ficiently perfect to show whether it supported lateral 

 cusps or not. If they were present, they must 

 have been of very small size. Under this uncer- 

 tainty it is impossible to determine whether this species should be 

 placed under the genus Lamna or Odontaspis ; but I am inclined, 

 from the slender subulate aspect of the teeth, to refer it to the 

 latter. At the time of writing this,'! have not been able to com- 

 pare the Indian specimens with figures of O. gracilis from the 

 chalk and 0. subulata from the lower greensand of Neufchatel ; 

 but the descriptions given of these species lead me to infer a con- 

 siderable resemblance in size and form with the Indian species, 

 although the latter has a very distinctive feature in the cessation 

 of the cutting edges before they reach the base, giving a con- 

 stricted appearance to the shaft of the tooth. This character is well 

 marked in Odontaspis contortidens of the Molasse ; indeed our 

 Pondicherry fossils are only distinguishable from this species by 

 the absence of the striae on the inner surface of the teeth. 



Odontaspis oxyprion Eg. — The last species I propose to 

 describe in this memoir is also frequent in the Indian collec- 

 tions. It belongs without doubt to the genus Odontaspis, and is i 

 very nearly allied to 0. rhaphiodon. The comparison, how- 

 ever, is less accurate than I could wishj owing to my not being able 

 to refer to Agassiz's plate on the subject ; but one character esta- 

 blishes at once the distinctness of the Indian species, viz. the absence 

 of striae on the inner surface of the tooth. Some of the specimens 

 of this species are in a good state of preservation, showing the form 

 of the base and the lateral cusps. It is not impossible that more 

 than one species may be included in this description, as some of the 

 specimens are more convex than others on the outer surface, and 

 less recurved at the point. The number and form of the lateral 

 cusps also vary considerably ; but there is a general resemblance 

 which induces me for the present to include all under one denomi- 

 nation. In the form of the central cone they agree very closely 

 with Odontaspis rhaphiodon; but the lateral cusps are largei*, 

 more elongated, and sharper at the points, and in these respects 

 they exceed even the recent Odontaspis ferox. They are some- 

 times single, sometimes double, on each side, and occasionally 

 single on one side and double on the other. The base is broader 

 and less deeply notched than in O. rhaphiodon. 



A considerable number of specimens remain to be examined ; 

 but most of them will probably belong to one or other of the species 

 described above. Should any distinct forms be found, they will 

 be treated of in a future memoir. 



