52 BULLETIN OF THE UNITED STATES FISH COMMISSION. 
This interesting species is based upon the following material: 
u.s. 
Nat. 
Mus. 
No. 
No. of 
sjjeci- 
mens. 
Locality. 
Date. 
Collector. 
43963 
- 13 
Rod Rock River, Rod Rock, Montana | 
July 27, 1891 
B. Clapham. 
43964 
13 
Beaverhead River, Dillon, Montana 
July 27, 1891 
Evermann &. Jenkins. 
185 
Whitewood Creek, Deadwood, South Dakota 
Oct. 6, 1892 
B. W. Evermann. 
45 
Spearfish Creek, Spearfish, South Dakota 
Oct. 7, 1892 
Do. 
3 
Chicken Creek, near Spearfish, South Dakota 
Oct. 8, 1892 
Do. 
5 
Crow Creek, (iamraon's Ranch, near Spearfish, South 
Dakota. 
Oct. 8, 1892 
Do. 
3 
Belle Eourclre River, Belle Fourche, South Dakota 
Oct. 11,1892 
Do. 
13 
Rapid Creek, Rapid, South Dakota 
Oct. 15,1892 
Do. 
Hat Creek, Ardmore, South Dakota :. 
Oct. 21,1892 
Do. 
In the report upon the explorations in Montana and Wyoming by Dr. O. P. 
Jenkins and myself, I hesitated to regard the specimens which we collected at Red 
Rock and Dillon as being new, and identified them as Catostomus discobolus Cope. 
The narrow foutanelle and the cartilaginous sheath of the lower lip, together with 
the uncertainty as to the exact locality from which Prof. Cope’s types came, seemed to 
favor this identification. Upon the suggestion of Dr. Jordan that the types of C. 
discobolus were probably the young of G. latipinnis and that my specimens were prob- 
ably an undescribed species, I was induced to make a reexamination of the question. 
This was particularly desirable in view of the fact that so much additional material 
had resulted from my recent explorations in the Black Hills. 
Prof. Cope’s types of Catostomus discobolus consisted of “ two specimens, one 
certainly, the other probably, from the Gfreen River, Wyoming,”* and can not now be 
found, but there are twelve specimens from the Colorado Basin in the Rational Muse- 
um under the name C. discobolus , presumably identified as such by Prof. Cope. These 
are quite certainly young specimens of Tantosteus delphinus, and I am inclined to the 
belief that the types of C. discobolus were also the young of this species rather than 
the young of C. latipinnis. Should this be the case, the species would stand as Tan- 
tosteus discobolus (Cope), discobolus having priority over delpliinus. 
While this question can not be definitely determined, Prof. Cope’s description of 
C. discobolus applying .equally well to C. latipinnis and P. delphinus , the probabilities 
are strongly in favor of this view, and I therefore adopt the name discobolus instead 
of delphinus for the Pantosteus of the Colorado River. 
As remarked elsewhere in this paper, all the other specimens in the Museum which 
have been called C. discobolus (and which are from Lapwai Creek, Idaho), are undoubt- 
edly young specimens of G. catostomus. 
An examination of the air bladder in several species of suckers shows marked 
differences. In all species of Pantosteus examined (P. generosus , plebeius , discobolus 
and jordani) the air bladder is quite small, the first (anterior) compartment being 
quite short, while the second is very long and slender, usually 2£ to 3 times the length 
of the first. 
In one specimen of P. discobolus the air bladder was large, but this specimen had 
been previously cut open and examined by some one; the air bladder was detached, 
and may possibly belong to another fish. 
’Hayden’s Geological Survey of Wyoming, 4th Annual Report, 1870, 435, 
