54 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
The collections made in 1889 in Colorado and Utah by Dr. Jordan and myself 
contain numerous specimens of Pantosteus from the Eio Grande, Colorado, and Utah 
basins, the study of which led Dr. Jordan to admit the three species, P. plebeius, 
generosus, and delphinus. He at this time regarded Acomus guzmaniensis as identical 
with P. plebeius, and P. virescens as being probably the same as P. delpliinus. 
These collections of 1889 suggested the strong probability of the limited distribution 
of each species of this genus, and that each is likely confined to a single hydrographic 
basin. My' examination of the types of all the nominal species now to be found, and 
the comparison with them of all the other material obtainable, confirm this view. I 
cau see no differences of any value among the specimens from the different places in 
the Eio Grande basin, and must regard them all as being identical with Baird and 
Girard’s Catostomus plebeius , the types of which came from the Eio Mimbres, a tribu- 
tary of Lake Guzman, which is in the Eio Grande basin. All the specimens from the 
Colorado basin are easily referable to P. delphinus (Cope), while all those from the 
Utah basin are with equal certainty P. generosus (Girard). 
The only specimen from the Arkansas basin is the type of Cope’s P. virescens , 
which is said to have been taken in the Arkansas Eiver at Pueblo, Colo. This 
specimen is about 14 inches in total length, and is in good condition. It is most 
closely related to P. discobolus, and, like that species, has a slender caudal peduncle 
and very small scales, which I count as 17-103-16, and 45 before the dorsal. I am 
not sure that this is really distinct from P. discobolus, and doubt if the specimen came 
from the Arkansas Eiver. 
The synonymy of the species of Pantosteus should stand as follows : 
PANTOSTEUS PLEBEIUS (B. & G.). 
Catostomus plebeius B. & G., Proc. Acad. Nat. Sci. Phila. 1854, 28 (Rio Mimbres, tributary of Lake 
Guzman, Chihuahua) ; Agassiz, Am. Jour. Sci. & Arts, 2d series, xix, 208, 1855. 
Minomus plebeius, Grd., Proc. Acad. Nat. Sci. Phila. 1856, 173 (Rio Mimbres, Chihuahua); ibid. . U. S. 
and Mex. Bound. Survey, 1858, 38, pi. xxm, figs. 6-10 (Rio Mimbres, Chihuahua). 
Catostomus plebeius, Gunther, Cat. Fishes, vii, 15, 1868 (Rio Mimbres). 
Pantosteus plebeius, Jordan & Gilbert, Synopsis, 122, 1883 (Lake Guzman); Jordan, Bull. U. S. F. C., 
ix, for 1889 (1891), 19 (Rio Conejos, Colo., and Rio Grande at Del Norte and Alamosa, Colo.). 
Catostomus ( Acomus ) guzmaniensis Grd., Proc. Acad. Nat. Sci. Phila. 1856, 173 (Janos River, tributary 
of Lake Guzman, Chihuahua). 
Acomus guzmaniemis Grd., U. S. and Mex. Bound. Survey, 1858, 39, pi. xxiii, figs. 6-10 (Janos River, 
Chihuahua). 
Catostomus guzmaniensis, Gunther, Cat. Fishes, Vii, 15, 1868 (Janos River, Chihuahua). 
Pantosteus jarrovii, Cope and Yarrow, Zoology Wheeler Survey, v, 674, pi. xxix, figs. 2 and 2a, 1875, 
only in part (San Ildefonso and Taos, New Mexico). 
Habitat : Eio Grande Basin. 
PANTOSTEUS VIRESCENS (Cope). 
Pantosteu^virescens Cope, Zool. Wheeler Survey, 1875, 675 (Arkansas River, Pueblo, Colo.); ibid., Jor- 
dan & Copeland, Check List, 1876, 156; ibid., Jordan, Bull. U. S. Geol. Surv. Terr., iv, 416, 
1878 (Arkansas River). 
Habitat: Arkansas Eiver. 
