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, 
^asciated with black. 
Stn. — Pimephales fasciattis, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, IS.'ie, 180. — Ibid. Gen. Ecp. Fishes, 234. 
Several of these small fish were obtamed at Milk river, Nebraska, where they are abundant. 
HYBOGNATHUS ARGYRITIS, Grd. 
silvery ITIinnow. 
Plate LIII, Figs. 5—8. 
Sp. Ch. — Body sub-fusiform in profile. Head sub-conical, contained five times and a half in the total length. Eye large 
and Sub-circular. Anterior margin of dorsal fin nparer the extremity of the snout than the base of the caudal. Insertion of 
ventrals equi-distant between the two points just alluded to in reference to the dorsal. Caudal fin entering four times and 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, greyish olive. 
Syn. — Hybognathus argyrilis, Gkd. in Proc. Acad. Nat. Sc. Philad. VIII, IS56, 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. Blackish brown above ; dirty or dull white beneath. 
SvN. — Argyrem nubilus, Gkd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 186. — Ibid. Gen. Rep. Fishes, 244. 
Two specimens were obtained at Fort Steilacoom, Washington Territory. 
POGONICHTHYS COMMUNIS, Grd. 
Nebraska Dace. 
Plate LV, Figs. 1—6. 
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 anterior 
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. 
SxN. — PogoniclUhys 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 ladarius 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. Boundaey, Fishes, Plate XXIX, Figs. 5 — 9. 
Sp. Ch. — Head constituting the fifth of the entire length in which the caudal fiu enters but four times and a half. Eye 
email, sub-elliptical, its borizontal diameter entering four times in the length of the side of the head. Body slender and tapering; 
46 Q 
