0. B. Eastman — Tamiobatis vetustus. 



87 



an elongated cavity, nor is it flanked by the compact rods of 

 rostral cartilage, usually so distinct in the skull of both fossil 

 and living skates. In fact, the tegmen cranii would seem to be 

 more completely closed than in either sharks or skates, such as 

 exist at the present day, or are known from the Mesozoic and 

 later rocks. It is scarcely necessary to remark that the sub- 

 stance composing the fossil is calcified cartilage, and the bare 

 spaces are where it has been weathered or worn away. The 

 crust has in places a thickness of about 3 mm ; superficially it is 



I Tamiobatis vetustus gen. et sp. nov. x£. AO, Antorbital process; F, Fon- 

 tacelle; FM, Foramen magnum; EM, Position of hyomandibular ; N, Nasal 

 capsules; PO, Postorbital process ; R. Rostrum. 



quite smooth and compact, but where partially abraded it is 

 seen to be composed of small aggregations which represent the 

 centers of calcification. No dental or integumentary structures 

 are to be observed. 



