SHARKS. 105 



quite harmless to man. It follows the shoals of Herrings, Pilchards, 

 and Sprats in their migrations, destroying incredible numbers; 

 when feeding it uses its long tail in splashing the surface of the 

 water, whilst it swims in gradually decreasing circles round a shoal 

 of fishes, which, thus kept crowded together, fall an easy prey 

 to their enemy. The Basking-Shark [Selache maxima, fig. 94), 



Fig. 94. 





Basking-Skark (Selache maxima). 



of which a male specimen 28 feet long, obtained near Shanklin, 

 Isle of Wight, is exhibited in the middle of the Gallery, is the 

 largest Shark of the North Atlantic, growing to a length of more 

 than 30 feet. It is quite harmless if not attacked, its food con- 

 sisting of small fishes and other small marine animals which swim 

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

 of the oil which is extracted from its liver, one fish (it is said) 

 •yielding from a ton to a ton and a half. Its capture is attended 

 with some danger, as one blow from its enormously strong tail 

 is sufficient to stave in the sides of a large boat. 



The Rhinodontidce comprise one species only, Tthinodon typicus, 

 a gigantic Shark which, though in most respects agreeing with the 

 ScylliiddB, resembles the Baaking-Sharks in the structure of its gills. 

 It is found in various parts of the Indian Ocean. The specimen 

 (18 feetjong) exhibited in the middle of the Gallery was procured 

 in Ceylon, and is quite young, — this species being known to exceed 

 a length of fifty feet; its teeth are very small, as in the Basking- 

 Shark, and, like that species, it is quite harmless. 



The Notidanidm are characterized by having only one dorsal 

 fin, without spine, opposite to the anal, and by lacking a nicti- 

 tating membrane or eyelid ; they contain two genera.— NoHdanus, 



