FISHES OF THE MISSOURI RIVER BASIN. 409 



dant, not only in the more open, swifter current, but in the more quiet nooks 

 among the dense growth of Chara and about the outlets of springs whose 

 water was very warm. This is a very interesting and remarkable fact, and 

 was not what we expected. Rhinichthys is a group of fishes whose species 

 seem to prefer cold water. If in any given region we wished to find Rhinichthys 

 wo looked for it in the coldest parts of the smaller streams, but here we 

 found it in the warmest parts of a very warm stream. 



75. Rhinichthys atronasus (Mitchill). Black-nosed Dace. This species has been 



reported from the Dakota River at Jamestown and La Moure, N. Dak., by 

 Woolman (1896). 



76. Hybopsis aestivalis (Girard). This species was found by us at Dunning, Nebr., 



in Middle Loup River, and at Ravenna, Nebr., in the South Loup River and 

 Mud Creek, from which, places II specimens were obtained. The largest of 

 these are 2k inches in total length. This species is readily distinguished 

 from H. gelidus by its much shorter, blunter snout, and larger eye; the color 

 is also different, both lobes of the caudal being pale and the fine dark dust- 

 ings are more evident on both back and sides, 



77. Hybopsis hyostomus (Gilbert). Blue River at Crete; Platte and Elkhorn 



rivers at Fremont (Meek, 1891). 



78. Hybopsis gelidus (Girard). Milk River (as Gobio gelidus type, Girard, 185Gand 



1858, and Suckloy, 18G0). Obtained by us at the following places: Powder 

 River, Arvada; North Platte River, Douglas; North Platte River, Grand 

 Island ; Bazile Creek, Niobrara ; White River, Chamberlain. Upon compar- 

 ing these specimens with those collected at St. Joseph, Mo., in 1881, by Drs. 

 Jordan and Meek, and which were identified by them as H. gelidus, we found 

 important differences and were disposed to regard our specimens as being an 

 undescribed species. But a reexamination of Girard's original description 

 showed that our specimens were the true H. gelidus, and that the St. Joseph 

 specimens had been erroneously referred to that species. These have since 

 been described by Jordan and Evermann 1 under the name Hybopsis mceki. 



The considerable number of excellent specimens which we have enables 

 us to give a more detailed description of 11. gelidus than has hitherto been 

 published. Head 4; depth 5; eye 6J; snout 2|; D. 8; A. 9; scales 6-14-4. 

 Body slender, not much compressed, back little arched, head long and 

 slender; mouth inferior, horizontal, broad, overhung by the very long pointed 

 snout, which is considerably decurved; barbel short, If in head; eyes very 

 small, high up, midway of head; interorbital width equal to width of mouth, 

 origin of dorsal a little nearer snout than base of caudal, directly over base 

 of vcntrals; free edge of dorsal fin slightly concave, the anterior ray but 

 little produced, its length 1* in head ; free edge of anal little concave, length 

 of first rays If in head ; pectorals much shorter than in H. mceki, 11 in head, 

 the first rays not produced or filamentous and not reaching ventrals; 

 vcntrals barely reaching vent, If in head; caudal very long and deeply 

 forked, the lobes as long as head, the lower slightly the longer. Lateral 

 line complete, straight ; teeth, 4-4, strongly hooked. Color, sides silvery, pale 

 below ; scales of back each with a group of fine dark specks on posterior 

 border, these extending almost to lateral line; rest of back and upper part 

 of sides sparsely dusted over with minute brownish specks; fins all pale 

 except the caudal, the lower lobe of which is dark, with a narrow white 

 border below ; upper lobe slightly dark at base. From Hybopsis meeki, which 

 it most closely resembles, this species may be distinguished by the much 

 longer and more pointed snout, tin; smaller eye, the much shorter pectoral 

 fins, and the darker coloration of the back. 



1 Fishes of Norili and Middle America, Part i, :!17, 1896. 



