550 FISHES. 



host, and merely seek for themselves a safe habitation^ feeding 

 on the animalcules which enter with the water the cavity 

 inhabited by them. 



IV. No ventral fins ivhatcvcr ; vent remote from the head ; 

 (jill-opcnings very wide, the gill-mciiibranes not heing united : 

 Ammodytina. 



The " Sand-eels " or " Launces " {Ammodytes) are ex- 

 tremely common on sandy shores of Europe and North 

 America. They live in large shoals, rising as with one accord 

 to the surface, or diving to the bottom, where they bury them- 

 selves with incredible rapidity in the sand. They are much 

 sought after for bait by fishermen, who discover their pre- 

 sence on the surface by watching the action of Porpoises 

 which feed on them. These Cetaceans, when they meet with 

 a shoal, know how to keep it on the surface by diving below 

 and swimming round it, thus destroying large numbers of 

 them. The most common species on the British coast is the 

 Lesser Sand-eel {A. tohianus) ; the Greater Sand-eel {A. 

 laneeolatus), which attains to a length of eighteen inches ; A. 

 sicidus, from the Mediterranean, scarcer in British seas. Two 

 species live on the American coasts, A. amei^icanus and A. 

 duhius ; one in California, A. personattis. Bleekeria from 

 Madras is the second genus of this group. 



V. No ventral fins vjhatcver ; vent remote from the head; 



Fig. 253. — Congrogadus subducens. 



gill-openings of moderate ividth, the gill-memhranes heing united 

 helow the throat, not attached, to the isthmus : CoNGEOGADiNA. 



Only two fishes belong to this group — Co7igrogadus from 

 the Australian coasts, and Haliophis from the Eed Sea. 



