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, 
fasciate'd with black. 
Syn .—Pimephales fascialus, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856,180.— Ibid. Gen. Pep. 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. 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 hearer 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. —Eybognathus argyrilus, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856,182 .—Ibid. Gen. Pep. 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.—H ead 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. 
Syn. — Argyreus nubilus, Grd. 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 LY, 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 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. — Pogoniclithys 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.—H ead 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 
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