448 



ZOOLOGY. 



yva6o;, jaw) is in allusion to the filaments or barbels grow- 

 ing out from the jaws, and which are characteristic of the 

 members of the group. The upper jaw is formed by the 



intermaxillary bones only, while 

 the supra-maxillary bones form 

 the bases of the large barbels. 

 The suboperculum is always ab- 

 sent, as is also the symplectic ; 

 the supra-occipital and parietal 

 bones are co-ossified. The skin is 

 either naked or with bony plates. 

 The air-bladder connects by a 

 duct with the roof of the oesoph- 

 agus. AVhile a few forms are 

 marine, most of the Siluroid 

 fishes are inhabitants of the riv- 

 ers of tropical countries, a large 

 number being characteristic of 

 the rivers of Brazil. All the 

 North American species belong to 

 the family Silv rides, of which 

 the common representatives aro 

 the horned pout and western 

 catfish. In these forms the skin 

 naked. The horned pout, 



is 



Fig. 405. Agpredo, a Silnroid fish, 

 seen from beneath, with its egg-cap- 

 sule's attached by slight stalks. 



ranges- 



Amiurus atrarius Gill, 

 from New England to Maryland 

 and the Great Lakes. It breeds in 

 New England in holes in gravel during the midsummer. The 

 Great Lake catfish, Amiurus nigricans Lesueur, is abundant 

 in the Great Lakes, and is about a metre (2-4 feet) in length. 

 The blind catfish, Gronias niyrilnliris Cope, inhabits a sub- 

 terranean stream tributary to Conestoga Eiver in Eastern 

 Pennsylvania. 



Among the exotic South American Siluroids are Arius 

 (Fig. 404) and Aspri'do (Fig. 405) of Guiana. In Arii/xand 

 some of its allies in South America the eggs are carried by 

 the males in their mouth, from five to twenty being thus 



