116 



LOWER VERTEBRATES. 



eight barbels. Nearly all the sixty or seventy known species inhabit the streams of 

 the East Indies, and of neighboring parts of Asia. Two of them, belonging to the 

 typical genus Porcus {Bagrus), are found in the Nile, and reach a length of five or 

 six feet. 



The Ictalurinse are the cat-fishes of North America. They are the only members 

 of the order which inhabit the fresh waters of our continent, and with the exception 



Fig. 79. — Silurus glanis, sheat-flsh (below); Lota lota, burbot (above). 



of one or two Asiatic species of Amiurus they are strictly confined to that region. 

 One species is known from Mexico, and another from Central America, while two or 

 three extend their range northward into the British possessions. With these excep- 

 tions the entire sub-family is confined to that part of the United States which lies 

 east of the Eocky Mountains, and within this region there is scarcely a permanent 

 stream or pond which has not one or more species of cat-fish, ' bull-head ' or ' horned- 

 pout.' 



The North American cat-fishes agree in having the skin everywhere entirely naked 



