FISHES OF COLORADO 1$ 



AA. Ventral fins inserted well forward, their origins quite near the origins of the pectoral fins ; 

 anterior portion of the dorsal fin always with spines. 



H. Body well covered with scales, which are regularly arranged; anal fin with spines. 

 I. Dorsal fin single, the spinous and soft portions always united. 



Family CENTRARCHIDAE, the Sunfishes and Bass, p. 93 

 II. Dorsal fins two, the spinous and soft dorsals completely separated or just touching at 



the base Family PERCIDAE, the Perch and Darters, p. 102 



HH. Body without scales, or at least not regularly and completely covered with scales; skin 

 more or less covered with minute prickles; anal fin without spines. 



Family COTTIDAE, the Sculpins, p. 113 



Superorder OSTARIOPHYSI 



The anterior vertebrae just back of the skull fused and modified, forming the 

 Weberian apparatus which connects the air bladder with the internal ear. Most 

 of the freshwater fishes are included in this group. 



Order Nematognathi 



The Catfishes and Related Forms 



Family SILURIDAE 



The Catfishes 



Body scaleless, with or without bony plates, skin very tough, frequently 

 silvery in color; barbels always present, often elongate; adipose fin generally 

 present; dorsal and pectoral fins usually with heavy spines. 



Catfishes are found in most of the fresh waters of the world and some species 

 are marine. They vary from forms like the little Stone Cat, Schilbeodes noc- 

 turniis (Jordan and Gilbert), which rarely exceeds three inches in length, to the 

 Wels, Silurus glanis L., of the Danube River, which reaches the length of nine 

 feet or more and a weight of four hundred pounds. Most species of Silurids have 

 heavy erectile spines in the dorsal and pectoral fins by means of which they can 

 inflict a painful wound. One species, Malapterurus eledricus (Gmelin), found in 

 the Nile River, can produce a powerful electrical discharge. Catfishes are par- 

 ticularly abundant in the tropical portions of Africa and South America. Eigen- 

 mann (1910) has listed three hundred species exclusive of related Nematognathi 

 from South America, nearly one-sixth of the entire fish fauna of that continent. 

 The total number of Catfishes has been estimated as about one thousand (Bou- 

 lenger, 1904). 



In the fresh waters of the United States about thirty species of Silurids are 

 found, three of which are known to occur in Colorado. Catfishes are not native 

 in the streams of the United States west of the Rocky Mountains, although they 



