SILUROID FISHES. 445 
yva0os, 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 cesoph- 
agus. While 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 Siluride, of which 
the common representatives are 
the horned pout and western 
catfish. In these forms the skin 
is naked. The horned pout, 
; Amiurus atrarius Gill, ranges 
_ cig 0 saad eel B84 som New England to Maryland 
sules attached by slight stalls. 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 nigrilabris Cope, inhabits a sub- 
terranean stream tributary to Conestoga River in Eastern 
Pennsylvania. 
Among the exotic South American Siluroids are Arius 
(Fig. 401) and Aspredo (Fig. 402) of Guiana. In Arius and 
some of its allies in South America the eggs are carried by 
the males in their mouth, from five to twenty being thus 
