PLATYGOBIO 171 



2 . 4 in its length. Color plain silvery, with a plumbeous luster along sides, 

 and traces of a dusky lateral stripe behind dorsal ; fins all plain ; young with 

 sides more or less punctulate with brown, suggesting the appearance of Hy- 

 bopsis hyostomus. Head 4 to 4 . 3 , broad and depressed and flat above, its 

 width 1 . 6 to 1 . 7 in its length; interorbital space 2 . 2 to 2 . 5 ; eye small, 

 3.9 to 4.6*; nose 2.7 to 3.1 in head, blunt, the muzzle overhanging 

 the inferior mouth; mouth rather large, nearly horizontal, tip of upper lip 

 below level of lower margin of orbit; barbel prominent, as a rule extend- 

 ing below cheek; lower jaw shorter than upper; isthmus narrow, scarcely 

 wider than pupil. Teeth 2, 4-4, 2, hooked and With masticatory surface; 

 peritoneum bright silvery. Dorsal fin with 8 rays, set a little in front of 

 ventrals and nearer muzzle than base of caudal; longest. dorsal ray 1 to 

 1 . 1 in head; anal rays 8, occasionally 9; pectorals long, pointed, f to £ to 

 ventrals; ventrals nearly to vent. Scales 6, SO-SS, 5, crowded forward, 

 21 to 23 rows before dorsal; lateral line complete, very little decurved. 

 Sexual differences not well known, probably not strongly marked. 

 A young male taken by us from the Ohio River had the snout tuber- 

 culate. 



This is a northwestern species whose occurrence once within the 

 limits of this state is to be taken as little more than an accident. 

 Some 20 specimens were collected by us in 1880 from the Illinois 

 River at Cairo, but it has not been otherwise -reported from any point 

 east of the Mississippi. Its territory of general distribution extends 

 throughout the Missouri River and its tributaries as far down as Kan- 

 sas City, and thence to the Saskatchewan, Assiniboin, Athabasca, 

 and McKenzie rivers, in the Dominion of Canada. A careful com- 

 parison of P. pallidus Forbes with specimens of the present species 

 obtained by Dr. Meek from the Missouri River at Sioux City, Iowa, 

 leads us to conclude that the two are identical, such differences as 

 are manifest being probably due to the immature condition of the 

 Ohio River specimens. 



This is said to be a fish of the river channels, and is not known to 

 ascend small streams. It is especially characteristic of the shallow 

 alkaline creeks of the Northwest. 



*Up to 6 in adults, according to Jordan and Eve.rmann. 



