14 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Large, black-spotted, both fore aud aft, aud reachiug a weight of 10 to 26 or 30 
pounds. Sea-run specimens are much paler in color and grow larger. 
b. Salmo niykiss dark! (Kichai’dsou). “Cnt-tliroat Trout.” 
The common trout of both sides of the Cascade Range, profusely aud usually 
rather finely spotted, the spots scarcely more numerous behind than before. 
c. Salmo mykiss lewisi (Girard). Trout of the Upper Mis,souri. (Plate II, Fig. 4.) 
This large trout seems to have tlie spots, on the average, larger than on those west 
of the mountains, but even this difference is questionable, and doubtless neither form 
requires a varietal name. 
d. Salmo mykiss heiishawi (Gill aud Jordan). The trout of Lake Tahoe aud neighboring waters. 
(Plate II, Pig. 5.) 
A fine large trout, distinguished mainly by its longer and more conical head. 
Spots large, equally distributed, extending on head aud belly. Scales rather small,' 
about 180. 
e. Salmo mykiss pleuriticus (Cope). Colorado Eiver Trout. (Plate II, Fig. 6.) 
The common trout of the basin of the Colorado, its range extending to the mount- 
ains of Arizona. Variable in color, size, and form, with its surroundings, and in most 
resiiects substantially identical with lewisi, the chief difference being that in this form, 
as in sirihirus, stomias, and macdonaldi, the black spots are usually much more numer- 
ous on the posterior jiart of the body, while the head is usually free from spots. This 
is, however, not universally true. 
In one specimen, from Trapper’s Lake, the entire body from head to tail is closely 
and coarsely spotted. Generally the black spots are rather large, but in some speci- 
mens the spots are small, smaller than in au 3 " of the other forms except var. macdonaldi. 
In a considerable number taken in Eagle River, Colorado, the spots are as small 
and as close set as in var. macdonaldi, aud the usual red color of the lower fins is in 
these specimens changed to pale orange. 
Although the coloration is almost that of macdonaldi, there are other differences, 
the most notable being in the short opercle, 4§ to 5 in head (4J in macdonaldi). The 
body is also less elongate than in macdonaldi. 
In var. pleuriticus there is almost always a very distinct red lateral band, and the 
lower fins are more or less red. 
f. Salmo mykiss spilurus (Cope). The Trout of the Eio Grande. (Plate III, Figs. 7 aud 8.) 
Abounding in all its tributaries aud extending southward in the mountains to 
northern Chihuahua. This form is apparently wholly identical Yav. pleuriticus 
except that in the specimens examined the scales are less crowded forward, so that 
the number in a lengthwise series is less. I count 155 to 160 in Rio Grande specimens ; 
185 to 190 in those from the Colorado. . From the trout of the Great Basin {virginalis), 
spilurns differs chieflj" in the arrangement of its spots. 
g. Salmo mykiss virginalis (Girard). (Salmo utah Sncklej.) The Trout of Utah Lake. (Plate III, 
Fig. 9.) 
The trout of the Great Basin are profusely aud not very coarsely spotted, the 
spots being numerous anteriorly as well as posteriorly, confined to the back rather 
than to the tail. In several examined, the scales are a little larger than in any of 
the other forms, 140 to 150 in a lengthwise series, the scales on the anterior part of 
