2 76 CHARACTERS OF VERTEBRATE ANIMALS 



Common Flying- Fish {Exoccetus volitans), found in all tropical 

 seas, has immensely elongated pectoral fins, which constitute the 

 so-called wings. 



1 3. Stickleback Family. — The familiar little fishes consti- 

 tuting this family are mainly, but not entirely, inhabitants of 

 fresh water, and are only found in the Arctic and North 

 Temperate zones. The name is derived from the fact that the 

 first dorsal fin is represented only by its spines, of which there 

 are a variable number. There are three common British species, 

 all of them nest-builders. Of these the largest is the Sea Stickle- 

 back (Gastrosteus spinackia), with fifteen spines. It also frequents 

 brackish water. The other two kinds live in fresh or brackish 

 water, the smaller being the Ten-spined Stickleback {Gastrosteus 

 ptmgitius) or "Tinker", while the other is the Three-spined 

 Stickleback [Gastrosteus aculeatus). 



14. Wrasse Family. — Wrasses are widely -distributed shore 

 fishes, being absent, however, from the polar regions, and are 

 especially numerous on rocky coasts and coral reefs. Most of 

 them are handsomely coloured, and some are pre-eminent among 

 fishes in this respect. The bones which constitute the bases of 

 the skeleton supporting the gill-arches (lower pharyngeal bones) 

 are fused together into a single tooth bearing piece. Many 

 members of the group are distinguished by the possession of 

 thickened lips, and all have blunt conical teeth suitable for 

 crushing the shells of molluscs and Crustacea, of which the food 

 consists. There are a number of British species, of which one 

 of the commonest is the Ballan Wrasse [Labrus maculatus), a 

 stoutly-built fish of some 15 inches long. The colour is of a 

 bright brown with numerous whitish spots, and touches of green 

 on the fore-part of the head and the bases of the fins. Some 

 individuals, however, are of a greenish colour all over. The 

 spiny first dorsal is long and low, while the soft second dorsal 

 is much shorter and higher. 



Sub-order 2. — Tuft-gilled Fishes (Lophobranchii) 



This small sub-order includes about 120 species of curiously 

 modified fishes, in which pelvic fins usually, and anal and caudal 

 fins commonly, have disappeared. The snout is drawn out into 

 a tube, at the end of which the small rounded toothless mouth 



