86 VERTEBRATE ANIMALS OF THE UNITED STATES 



large: over 900 species and 100 genera, most of which are fresh water 

 fish Hving in the warmer regions of Africa and South America, especially 

 the Amazon region; a few species marine, mostly in tropical waters; 

 about 30 species in the United States, none of which are on the Pacific 

 slope except a few which have been introduced. 



Key to the Genera of Ameiuridae in the United States 



ai Posterior margin of adipose fin not adnata to back, 

 bi Rays of anal fin 17 to 35. 



Ci Complete bony ridge extending from the head to the dorsal 



fin I . Ictalurus. 



C2 Bony ridge from head to dorsal fin interrupted. 



, di Tail fin forked 2. Villarius. 



do Tail fin truncate or lunate. 



ei Eyes normal 7^. A meiurus. 



62 Eyes under the skin; cave fishes 4. Gronias. 



hi Rays of anal fin 1 2 to 1 5 5. Opladelus. 



az Posterior margin of adipose fin adnate to back; size small or very 

 small. 



bi Adipose fin separated from caudal fin by a distinct notch 6. Noturus. 



hi Adipose fin not separated from caudal fin. 



Ci Pectoral spines not serrate 7. Schilbeodes. 



C2 Pectoral spines more or less serrate 8. Rahida. 



I. Ictalurus Rafinesque. Channel cats. Body slender; head 

 conical; mouth small; supraoccipital process prolonged posteriorly, 

 its emarginate end receiving the anterior tip of the second interspinal, 

 thus forming a continuous bony ridge between the head and the dorsal 

 fin; rays of dorsal fin usually I, 6; caudal fin deeply forked; 8 barbels 

 present: 4 species, i in Guatemala, all important food fishes. 



Key to the United States Species of Ictalurus 



ai Body not spotted. 



bi Anal fin with 32 to 35 rays /. fiircatiis. 



hi Anal fin with 24 to 26 rays /. anguilla. 



a2 Body spotted /. punctatus. 



I. furcatus (Cuvier and Valenciennes). Great forked-tail cat (Fig, 

 39). Extreme length 1,500 mm.; extreme weight 150 lbs.; average 

 weight 10 lbs. ; head 4.5 ; depth 5 ; color silvery; anal fin almost one third 

 the length of the body: Mississippi Valley and Gulf States; northward to 

 Iowa and Ohio; abundant in the south. 



/. punctatus (Raf.). Channel cat; spotted cat (Fig. 40). Extreme 

 length 900 mm.; extreme weight 25 lbs.; head 4; depth 5; color oli- 

 vaceous, with small irregular round black spots; anal fin with 25 to 



