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 ivhatever ; vent remote from the head ; 

 gill-openings very wide, the gill-membranes 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. 

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

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

 species live on the American coasts, A. americanus and A. 

 dubius ; one in California, A. personattis. Bleeheria from 

 Madras is the second genus of this group. 



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



.^J>* .'■■■■• • .... -J-J 



Fig. 253. — Congi'Ogadus subduoens. 



gill-openings of moderate width, the gill-membranes heing united 

 below the throat, not attached to the isthmus : CoNGROGADlNA. 



Only two fishes belong to this group — Gongrogadus from 

 the Australian coasts, and Haliophis from the Eed Sea. 



