FISHES 85 



50. Platygobio Gill. Body elongate, somewhat compressed; teeth 

 2, 4-4, 2; head broad and flat; a barbel on each maxillary; rays of both 

 dorsal and anal fins 8; scales large: 2 species. 



P. physignathus (Cope). Length 150 mm.; head and depth 4.6; 

 color olivaceous, with a plumbeous lateral band; belly white; scales 

 6-48-5, 20 before the dorsal fin; body slender: upper waters of the 

 Arkansas; very common in the river channels. 



P. gracilis (Richardson). Flatheaded chub. Length 300 mm.; 

 head 4.25; depth 4.75; color pale olive; head white; scales 6-50-5, 23 

 before the dorsal fin: head waters of the Missouri and Yellowstone to 

 the Saskatchewan; eastward to Kansas City; common in river channels. 



51. Exoglossum Rafinesque. Body moderately elongate; the two 

 sides of the lower jaw united its whole length, instead of forming a 

 broad arch, and looking like a projecting tongue; teeth i, 4-4, i: i 

 species. 



E. maxillingua (LeSueur). Cut-lip; nigger chub. Length 150 mm.; 

 head 4; depth 4.5; color olivaceous; a black bar behind the opercle; 

 rays of dorsal fin 8; anal 7; scales 8-53-5 : St. Lawrence River and Lake 

 Ontario to Virginia; locally abundant. 



Order 4. Heterognathi. — The four anterior vertebras modified 

 and coossified, and Weberian ossicles present; fins soft-rayed; lower 

 pharyngeals not falciform; ventral fins abdominal; no pseudobranchiae : 

 2 families of tropical fishes, represented by a single species in Texas. 



Family Characinidae. — Adipose fin present; head naked; scales 

 cycloid : 300 species. 



Astyanax Baird and Girard. Body oblong, compressed ; lateral line 

 complete; premaxillary teeth in a double row: 40 species. 



A. mexicamis (Filippi). Head 4; depth 3; color olivaceous, with 

 a lateral silvery band and a black caudal spot; rays of dorsal fin 10; 

 anal 21; scales 6-38-6: southern Texas and Mexico; abundant. 



Order 5. Nematognathi. — Catfish. The four anterior vertebrae 

 modified and with Weberian ossicles; no subopercle; ventral fins 

 abdominal; fins soft rayed, except the dorsal and pectoral fins, each 

 of which has a single spine; scales wanting, the skin being naked or 

 with bony plates; the border of the mouth formed by the premaxillaries, 

 the maxillary being often rudimentary; barbels present on the maxil- 

 laries: several families, i in the fresh waters of America. 



Family Ameiuridae. — Body elongate, naked; upper jaw formed of 

 premaxillaries alone; maxillaries rudimentary; barbels 8, on anterior 

 part of head; adipose fin present; a stout spine forms the anterior 

 ray of dorsal and pectoral fins; lower pharyngeals separate; air bladder 



