322 FISHES. 



Alopecias. — The second dorsal and anal very small. Caudal 

 fin of extraordinary length, with a pit at its root. No keel on 

 the side of the tail. Mouth and gill-openings of moderate width. 

 Teeth equal in both jaws, of moderate size, flat, triangular, not 

 serrated. 



This genus consists of one species only, which is known 

 by the name of " Fox-shark " or " Thresher." It is the most 

 common of the larger kinds of Sharks which occur on the 

 British coasts; and seems to be equally common in other 

 parts of the Atlantic and Mediterranean, as well as on the 

 coasts of California and New Zealand. It attains to a length 

 of fifteen feet, of which the tail takes more than one half ; 

 and is quite harmless to man. It follows the shoals of Her- 

 rings, Pilchards, and Sprats in their migTations, destroying 

 incredible numbers. When feeding it uses the long tail in 

 splashing the surface of the water, whilst it swims in gradu- 

 ally decreasing circles round a shoal of fishes, which are thus 

 kept crowded together, falling an easy prey to their enemy. 

 Statements that it has been seen to attack Wliales and other 

 large Cetaceans, rest upon erroneous observations. 



Selachb. — The second dorsal and anal very small. A pit at 

 the root of the caudal fin, which is provided with a lower lobe. 

 Side of the tail with a keel. Gill-openings extremely wide. Teeth 

 very small, numerous, conical, without serrature or lateral cusps. 



Also this genus consists of one species only, the " Basking 

 Shark " (P^lerin of the French). It is the largest Shark of 

 the North Atlantic, growing to a length of more than thirty 

 feet. It is quite harmless if not attacked ; its food consisting 

 of small fishes, and other small marine animals swimming in 

 shoals. On the west coast of Ireland it is chased for the sake 

 of the oil which is extracted from the liver, one fish yielding 

 from a ton to a ton and a-half. Its capture is not unattended 

 with danger, as one blow from the enormously strong tail is 

 sufficient to stave in the sides of a large boat. At certain 



