ZOOLOGY. 361 



the side of the head. Posterior extremity of maxillar bone not extending as far as a vertical line drawn in advance of the 

 orbit. Extremities of ventrals stretching beyond the anterior edge of the anal. Scales deeper than long, elliptical ; brown, 

 fasciated with black. 



SYN. Pimephdes fagciatus, GRD. in Proc. Acad. Nat. So. Philad. VIII, 1856, 180. IBID. Gen. Rep. Fishes, 234. 



Several of these small fish were obtained at Milk river, Nebraska, where they are abundant. 



HYBOGNATHUS ARGYRITIS, Grd. 



Silvery Minnow. 



PLATE LIII, FIGS. 58. 



SP. Cn. Body sub-fusiform in profile. Head sub-conical, cont lined five times and a half in the total length. Eye large 

 and sub-circular. Anterior margin of dorsal fin nearer the extremity of the snout than the base of the caudal. Insertion of 

 ventrals equidistant between the two points just alluded to in reference to the dorsal. Caudal fin entering four times and a half 

 in the total length. Scales anteriorly sub-truncated. Olivaceous brown above, yellowish beneath, with a silvery streak along 

 the middle of the flanks. Fins unicolor, grayish olive. 



SYN. Hybognathus argyritus, GKD. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 182. IBID. Gen. Rep. Fishes, 235. 



A few of these small fishes were taken from pools along the almost dry bed of Milk river, 

 Nebraska. 



ARGYREUS NUBILUS, Grd. 



SP. CH. Head rather small, constituting the fifth of the entire length. Mouth small, and barbel inconspicuous ; lips 



cartilaginous. Eye moderate sized, sub-circular ; its diameter entering five times in the length of the side of the head. Anterior 



margin of dorsal fin nearer the extremity of the snout than the tip of the middle rays of the caudal. Insertion of ventral fins 



equidistant between the angle of the mouth and the base of the caudal. Blackit-h brown above ; dirty or dull white beneath. 



S?y.Arffyreus nubilus, GRD. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 186.--IB1D. Gen. Rep. Fishes, 244. 



Two specimens were obtained at Fort Steilacoom, Washington Territory. 



POGONICHTHYS COMMUNIS, Grd. 



Nebraska Dace. 



PLATE LY, FIGS. 16. 



SP. CH. Head forming a little less than the fifth of the total length, its upper surface quite depressed in the adult. 

 Snout rounded, depressed, and quite protruding. Gape of mouth nearly horizontal ; lower jaw shorter than the upper. Poste 

 rior extremity of the maxillary extending to a vertical line drawn in front of the orbit. Anterior margin of dorsal fin much 

 nearer the extremity of the snout than the base of the caudal. Insertion of ventrals placed somewhat posteriorly to the ante 

 rior margin of the dorsal, their anterior basal edge being nearer the tip of the snout than the base of the caudal. Lobes of 

 caudal fin equally developed. Reddish gray above ; whitish or yellowish beneath, with metallic reflects. Fins yellowish olive. 



SYN. Pogonichthys communis, GRD. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 188. IBID. Gen. Rep. Fishes, 247. 

 Found in sunken pools and lagoons along the line of Milk river, Nebraska, under similar 

 circumstances as the Acomus lactarius already referred to. The species rarely attains a greater 

 length than six or seven inches, and is of very indifferent quality for the table. A characteristic 

 by which the fish may be readily recognized is the large size of its nostrils. 



GOBIO GELIDUS, Grd. 

 U. S. & MEX. BOUNDARY, FISHES, PLATE XXIX, FIGS. 5 9. 



SP. CH. Head constituting the fifth of the entire length, in which the caudal fin enters but four times and a half. Eye 

 small, sub-elliptical, its horizontal diameter entering four times in the length of the side of the head. Body slender and 



46 Q 



