456 PARENTAL CARE AMONG FRESH-WATER FISHES. 



r 

 about eight hundred species being Ivnown. The form is more or less 

 elongated and the trunk naked, at most plates existing only along the 

 lateral line. The head is either naked in some or shielded in others, 

 but with the opercular apparatus well developed. The mouth is 

 normal and has simple lips; maxillary barbels are conspicuous; 

 the dorsal fin, when developed, is near the head and has a sjoine, but 

 in some is atrophied or entirely suppressed. Coincident with these 

 are certain osteological characters which reenforce the family value 

 of the group. 



The European species belong to the subfamily of Silurines, which 

 are distinguished by the great length of the tail and anal fin and the 

 advanced position of the anus as well as the small or atrophied dorsal 

 fin; there is no adipose fin. The species are confined to the Old 

 World and are numerous in Asiatic and African rivers. 



The North American species represent another subfamily — Ictalu- 

 rines — distinguished by the moderate length of the tail and anal fin, 

 the submedian position of the anus, the well-developed dorsal fin and 

 spine, and the presence of an adipose or fatty fin along the back of 

 the tail; the barbels are eight in number, the usual maxillary and 

 chin being supplemented by a pair of small ones close behind the 

 hinder nostrils ; further the two pairs of nostrils are quite far apart ; 

 the palate is toothless. Catfishes of this kind are nearly confined to 

 North America, few species extending into Central America and 

 northeastern Asia. Between thirty and forty occur in the streams 

 and lakes of America. 



The South American and most of the Mexican species are closely 

 related to the North American, and have the same form and fins, but 

 there are only six barbels, the nasal being absent ; as in them, however, 

 the anterior and posterior pairs of nostrils are far' apart. 



The marine catfishes, designated as Tachisurines or Ariines, differ 

 very little from the preceding, having essentially the same from and 

 proportions as well as fins, but the two pairs of nostrils are close 

 together, there are no nasal barbels, and the palate is armed with small 

 and densely crowded teeth. Numerous species inhabit tropical seas 

 near the land, and a few enter fresh-water streams. 



All these are closely related and thus may be brought together in 

 this connection. Another subfamily is more distant. 



THE DORADINES OF SOUTH AMERICA. 



Next may be noticed South American Silurids (Doradines), espe- 

 cially distinguishable superficially by the existence of a single row of 

 plates along the sides, and thus separated from the other groups of 

 the family to which they belong as well as from the Callichthyids, 

 with which they are often confounded by the natives of the countries 



