go RECENT SHARKS 
ment of teeth and shagreen denticles ; the calcification of 
the vertebra (great differences sometimes occurring in the 
same genus, e.g. Scyl/ium), the size, disposition, and num- 
Fig.96.— The mackerel shark, Lamna cornubica (Gmel.), Fleming. X %. 
North Atlantic, 
ber of the fins, the more or less pouch-like character of 
the sensory canals. . 
In the basking shark, Cetorhinus (Selache) (Fig. 96 A), 
widely specialized conditions occur in the gill rakers, 
which enable the throat to retain the smallest food organ- 
Fig. 96 A.— The basking shark, Ceforhinus maximus, (L.) Bainville. ¢. 
X go. (After GOODE in U. S. F. C.) 
isms. In another shark, Lemargus (Fig. 96 B), the eggs 
are probably fertilized after being deposited, — a condition 
unique among recent Elasmobranchs. 
