90 



RECENT SHARKS 



ment of teeth and shagreen denticles ; the calcification of 

 the vertebrae (great differences sometimes occurring in the 

 same genus, e.g. Scyllmm), the size, disposition, and num- 



Fig. 96. — The mackerel shark, Lamna cornubica (Gmel.), Fleming. X zV. 



North Atlantic. 





ber of the fins, the more or less pouch-like character of 

 the sensory canals. 



In the basking shark, Cetorhhius (Selache) (Fig. 96 A)y 

 widely specialized conditions occur in the gill rakers, 

 which enable the throat to retain the smallest food organ- 



Fig. 96 A. — The basking shark, Cetorhinus maximus, (L.) Blainville. cT. 

 X eV (After GOODE in U. S. F. C.) 



isms. In another shark, Lcemargus (Fig. 96 B)^ the eggs 

 are probably fertilized after being deposited, — a condition 

 unique among recent Elasmobranchs, 



