EXPLORATIONS IN YELLOWSTONE NATIONAL PARK. 
49 
which Hows into tlie Snake River lower down. This species is allied to Leiiciseus man- 
taiius (= CUnostomm tmnia) Cope, ditt'eriug' chiefly in the longer anal, sharper snout, and 
smaller eye. In technical characters it has much in common with Bichardsonius later- 
alis, which suggests that Bichardsonius may be a near ally of the Clinostonms grou[) 
of the genus called Leuciscus. 
Head, Tl in length ; depth, 3| to 4. Anal 2, 13 ; lat. 1. 55. Color silvery, a plum- 
beous lateral band, dusted with dark points; traces of red coloration on belly in 
largest specimen. Lateral line much decurved. Pectoral and ventral fins long and 
falcate. Base of anal 6.]- in body; lower jaw slightly ])rojectiug ; upper jaw less blunt 
and decurved tl)an in L. montanus. Eye as long as snout; 3^ in head (young). 
7. Coregonus williamsoni Girard (var. cinmontanus.) (Plate IX, Fig.s. Sand 9.) 
The mountain whilefish is abundant in the Madison River below the falls. It is 
said to be equally common in the Yellowstone River, but none were obtained by ns. 
It is a slender and graceful fish, readily taking the fly like a grayling or trout. It is 
most abundant, so far as we have noticed, in the eddies or deeper places in swift 
streams. It seems to be essentially a river fish, rather than an inhabitant of lakes. 
Comparing our specimens from Horsethief Creek, a tributary of Madison River, with 
others collected at Walla Walla (Washington, Captain Bendire), these specimens from 
the Missouri seem notably different, the body being much more slender and the tins 
shorter. In coloration, and in the form of the head, mouth, and eye, there is sub- 
stantial agreement. 
In the Madison River specimens, the depth is 5 to 5| in the length, the head 5, 
the iiectoral, in head, the ventral If, the longest dorsal ray, 1^, the scales, 90. In 
the Walla Walla fishes, the depth is 4^ to 4|, the head 4|, the pectoral li, the ventral 
1|, the dorsal IJ, the scales 83. Specimens from the Willamette River at Salem, Ore- 
gon, and others from Jordan River and Provo River in Utah, agree in these respects 
with the specimens from Walla Walla. 
If these differences should prove at all constant, the Missouri River whitefish 
should stand as a distinct variety, Coregonus tvilliamsoni cismontanus. The type of 
Coregonus couesi Milner, is from Chief Mountain Lake, Montana, a tributary to the 
Saskatchawan on the east side of the Divide. This specimen, lately examined by me, 
shows the prolonged snout characteristic of the males in the breeding season. In all 
respects, so far as I can see, it agrees with the typical form of Coregomis ivilliamsoni 
and not with the variety found in the Park. Its scales are 84; the pectoral is 1 l in 
the head, 5^- in the body ; the veutrals are IJ- in head. The depth 4J in length ; the 
dorsal is broken. C. icilliamsoni much resembles C. quadrilateralis, but the latter has 
a smaller mouth and the gill-rakers notably shorter and thicker. 
8. Thymallus signifer Richardson. (Var. ontariensis.) (Plate VIII, Pig. 7.) 
The Grayling is very abundant in the Madison River below the junction of the 
Firehole and the Gibbon. Numerous specimens were collected for us in Horse Thief 
Spring, a, small stream just outside the limits of the Park, by Mr. Lucas. The gray- 
ling is said to ascend the river in summer as far as the Firehole Falls and Gibbon 
Falls. It is said also to be found in the Gallatin River, in the northwestern part of 
the Park. 
We have carefully compared our specimens with others collected by Judge D. D. 
Bauta, in Otter Creek, in the Keweenaw Peninsula, and with a specimen from An Sable 
Bull. U. S. F. C., 89 4 
