The True Sharks 197 
an ordinary whaleboat. The basking shark is known on all 
northern coasts, but has most frequently been taken in the 
North Sea, and about Monterey Bay in California. From this 
locality specimens have been sent to the chief museums of 
Europe. In its external characters the basking shark has much 
in common with the man-eater. Its body is, however, rela- 
Fic. 189.—Basking Shark, Cetorhinus maximus (Gunner). France. 
tively clumsy forward; its fins are lower, and its gill-openings 
are much broader, almost meeting under the throat. The 
great difference lies in the teeth, which in Cetorhinus are very 
small and weak, about 200 in each row. The basking shark, 
also called elephant-shark and bone-shark, does not pursue its 
prey, but feeds on small creatures to be taken without effort. 
Fossil teeth of Cetorhinus have been found from the Creta- 
ceous, as also fossil gill-rakers, structures which in this shark 
are so long as to suggest whalebone. 
Family Rhineodontide. — The whale-sharks, Rhineodontide, 
are likewise sluggish monsters with feeble teeth and keeled 
tails. From Cetorhinus they differ mainly in having the last 
gill-opening above the pectorals. There is probably but one 
species, Rhineodon typicus, of the tropical Pacific, straying north- 
ward to Florida, Lower California, and Japan. 
The Carcharioid Sharks, or Requins._- The largest family cf re- 
cent sharks is that of Carchariide (often called Galeorhimde, 
or Galeide), a modern offshoot from the Lamnoid type, and 
especially characterized by the presence of a third eyelid, the 
nictitating membrane, which can be drawn across the eye from 
