EXPLORATIONS IN COLOKAOO AND tITAIi. 
11 
FISHES OF THE ARKANSAS BASIN. 
A. — UPPER ARKANSAS ABOVE THE CANON. 
1. Catostomus teres sucklii Girard. G., T. (Catostomns alticolus Co])e ; Moxostomatrisigitatum Copo.) 
Abundant in Lake Greek, and more or less common in the Twin Lakes. Similar 
to ordinary eastern specimens — var. teres — except that the lips are larger, and the 
upper lip has from four to six rows of papillm. The fish called Catostomus sucklii by 
Girard belongs to this type, which may be known as var. sucklii. 
2. Rhinichthys dulcis (Girard). L., T., G. 
Abundant in all the streams tributary to the Upper Arkansas, in company with 
the trout, although not ascending the brooks as far as the lakes. 
3. Cottus sp. 
It is said that a species of Cottus is occasionally found in the Upper Arkansas, 
but we saw no specimens. 
4. Salmo mykiss macdonaldi (Jordan and Evermaiin). The yellow-finned trout of Twin Lakes. 
(Plate I, Fig. 1.) 
Besides the common green-back trout another trout has long been known to 
anglers to exist in Twin Lakes, and Messrs. Gordon Land and George R. Fisher have 
in one way or another at difi'erept times called attention to it. 
Mr. Fisher accompanied me from Leadville in search of the fish, and a morning ol 
fly-fishing secured for us about ten fine specimens. These represent a very distinct 
form or variety of the mountain trout, whicli we recognize as a distinct subs])ecies 
under the name of Salmo mykiss macdonaldi. We have taken pleasure in naming the 
yellow-fin for the U. S. Fish Commissioner, the Hon. Marshall McDonald, in recogni- 
tion of his services in connection with the propagation of the American Salmonidie. 
It is not unlikely that this may prove to be a desirable variety for introduction 
into gravelly ponds and lakes in other regions. 
Description. — Head, 4 to 4 1.10 in length ; depth, 4 1.5 to 5. D. 2, 12. A. 1, 11. B. 
10. Scales, 40-184-37 ; about 125 pores. Length of types, 6 to 10 inches. 
Body more elongate and more comiiressed than usual among the trout. Head 
long, compressed, the snout moderately pointed ; mouth rather large, the jaws sub- 
equal, the maxillary extending beyond the eye, l^ to 2 in head; hyoid teeth present, 
small; opercle longer than usual, its greatest length 4.V in head, somewhat greater 
than eye, its posterior margin strongly convex. Eye 5^ in head ; snout 4J ; gill- 
rakers short, a? -F 10 in number. 
Scales quite small and regularly placed. Pectoral fin moderate. If in head ; ven- 
trals 2. Caudal moderately emargiuate, the lobes equal. If in head. 
Color, silvery olive; a broad lemon yellow shade along the sides, lower fins bright 
golden yellow in life, no red anywhere except the deep red dash on each side of the 
throat, which is never wanting in Salmo mykiss. Body posteriorly and on dorsal and 
candal fin profusely speckled with small pepper-like spots, smaller than the nostril 
and smaller than in any other of the forms of the Salmo mykiss. Occasionally these 
spots extend forward to the head, but they are usually sparse on the anterior half of 
the body. 
