The Nematognathi, or Catfishes 185 



waters as Ameiurus nebulosus, brought from the Potomac and 

 by Chinese carried from San Francisco. 



The Hypophthalmidae and Pygidiidae. The Hypophthalmidcu 

 have the minute air-bladder inclosed in a long bony capsule. 

 The eyes are placed very low and the skin is smooth. The 

 statement that this family lacks the auditory apparatus is not 

 correct. The few species belong to northern South America. 



Allied to this group is the family Pygidiidcs with a differ- 

 ently formed bony capsule and no adipose fin. The numerous 

 species are all South American, mostly of mountain streams 

 of high altitude. Some are very small. Certain species are 

 said to flee for protection into the gill-cavity of larger cat- 



FIG. 147. An African Catfish, Chlarias brenceps Boulenger. Congo River. 

 Family Chlariidce. (After Boulenger.) 



fishes. Some are reported to enter the urethra of bathers, 

 causing severe injuries. The resemblance of certain species 

 to the loaches, or Cobitida, is very striking. This similarity 

 is due to the results of similar environment and necessarily 

 parallel habits. The Argidoz have the capsule of the air-bladder 

 formed in a still different fashion. The few species are very 

 small, inhabitants of the streams of the high Andes. 



The Loricariidse. In the family of Loricariidaz the sides and 

 back are armed with rough bony plates. The small air-bladder 

 is still in a bony capsule, and the mouth is small with thick 

 fringed lips. The numerous species are all small fishes of the 

 South American waters, bearing a strong external resemblance 

 to Agonida, but wholly different in anatomy. 



The Callichthyidae. The Callidiikyidcc are also small fishes 

 armed with a bony interlocking coat of mail. They are closely 

 allied to the Pygidiida. The body is more robust than in the 

 CallichikyidcB and the coat of mail is differently formed. The 

 species swarm in the rivers of northern South America, where 



