404 The Nematognathi, or Catfishes 
waters as Ameiurus nebulosus, brought from the Potomac and 
by Chinese carried from San Francisco. 
The Hypophthalmide and Pygidiide.—The Hypophthalmide 
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 Pygidiide 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- 
Fic. 316.—An African Catfish, Chlarias brevceps Boulenger. Congo River. 
Family Chlariide. (After Boulenger.) 
fishes. Some are reported to enter the urethra of bathers, 
causing severe injuries. The resemblance of certain species 
to the loaches, or Cobitide, is very striking. This similarity 
is due to the results of similar environment and necessarily 
parallel habits. The Argid@ 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 Loricariide.—In the family of Loricariide 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 Agonide, but wholly different in anatomy. 
The Callichthyide.— The Callichthyide are also small fishes 
armed with a bony interlocking coat of mail. They are closely 
allied to the Pygiditde. The body is more robust than in the 
Callichthyide and the coat of mail is differently formed. The 
species swarm in the rivers of northern South America, where 
