SILURID^ THE CATFISHES 173 



very small forms are of more or less value as food. The giant 

 "sheatfish," or "wels," of Europe, which is abundant in the Danube, 

 reaches a weight of 300 to 400 lb, being next after the sturgeons 

 the largest European fish. There are in the United States, Canada, 

 and Mexico upwards of 35 species of catfishes, three genera and 

 12 species of which are found in the waters of the Mississippi 

 Valley. It is a remarkable fact that ' no catfishes are found 

 indigenous to the waters of the United States west of the Rocky 

 Mountains, although several species have recently been introduced 

 there by the United States Fish Commission. No extinct forms of 

 importance are known. A few remains have been recovered from 

 the lower and middle Eocene and Tertiary. The evidence from 

 paleontology (chiefly the absence of fossils) and from the anatomy 

 of the living forms, indicates that the catfishes are a recent group, 

 derived doubtless from scaly ancestors, and probably related to the 

 Characinidm or Cyprinida. 



The catfishes are mainly dwellers in more or less muddy water, 

 making their home most of the time upon the bottom and chiefly 

 feeding there. Agreeably to this habit, their eyes are small, and 

 their cuticular sensory organs are highly developed. The family, 

 taken together, is nearly omnivorous in habit, and their alimentary 

 structures have a correspondingly generalized character. The capa- 

 cious mouth, the wide oesophagus, and the short, broad stomach 

 admit objects of relatively large size and of almost any shape. The 

 jaws, each armed with a broad pad of fine sharp teeth, are well cal- 

 culated to grasp both hard and soft bodies. The gill-rakers are of 

 average number and development, and the pharyngeal jaws — 

 broad, stout arches below and oval pads above, with their opposite 

 surfaces covered with minute, pointed denticles — serve well to crush 

 the crusts of insects and the shells' of the smaller mollusks. The 

 indifference of several of the species to the past history or the present 

 condition of their food distinguishes them as the most important 

 scavengers among our common fishes. With the eel, they are to be 

 considered among the most destructive enemies of shad in the streams 

 of the Atlantic coast, as is proven by the contents of stomachs of 

 many specimens taken over the spawning grounds of that fish. Most 

 of the species are nocturnal, remaining more or less sluggish through- 

 out the day. In winter they appear to .take little or no food. 

 Their extreme tenacity of life and omnivorous habit favor their 

 multiplication in almost any kind of situation, often enabling them 

 to survive through drought or other hardships to which all their 

 -neighbors succumb. 



