SILURID^E THE CATFISHES 173 



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 Characinidce or 

 CyprinidoB. 



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 corresponding generalized 

 character. The capacious 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 calculated to grasp both hard and 

 soft bodies. The gill-rakers are of average number and develop- 

 ment, 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 con- 

 dition 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 throughout the day. In winter they appear to 

 take little or no food. Their extreme tenacity of life and om- 

 nivorous 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. 



All except the smaller catfishes, the stonecats, are used for 

 food, and the best of them rank well among river fishes for edible 

 qualities. The bullheads are mostly consumed locally, as pan- 



