PLATYGOBIO 171 



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 Hybopsis hyostomus. 

 Head 4 to 4.3, broad and depressed and fiat 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 extending 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, % to ^5 to ventrals; ventrals nearly to vent. Scales 6, 50-55, 

 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 tuberculate. 



This is a northwestern species whose occurrence once within 

 the limits of this state is to be taken as little more than an acci- 

 dent. Some 20 specimens were collected by us in 1880 from the 

 Ohio River at Cairo, but it has not been otherwise reported from 

 any point east of the Mississippi. Its territory of general dis- 

 tribution extends throughout the Missouri River and its tribu- 

 taries as far down as Kansas City, and thence to the Saskatche- 

 wan, Assiniboin, Athabasca, and McKenzie rivers, in the Do- 

 minion of Canada. A careful comparison 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 con- 

 clude 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 Evermann. 



