318 Salmonidz 
to be more favorable to hybridism than in others in which 
hybrids are of comparatively rare occurrence. Hybrids be- 
tween the salmon and other species are very scarce everywhere.” 
Very similar to the European Salmo trutta is the trout of Japan 
(Salmo perryt), the young called yamabe, the adult kawamasu, 
or river-salmon. This species abounds everywhere in Japan, 
the young being the common trout of the brooks, black-spotted 
and crossed by parr-marks, the adult reaching a weight of ten 
or twelve pounds in the larger rivers and descending to the sea. 
In Kamchatka is another large, black-spotted, salmon-like 
species properly to be called a salmon-trout. This is Salmo 
mykiss, a name very wrongly applied to the cutthroat trout of 
the Columbia. 
The black-spotted trout, forming the subgenus Salar, difter 
from Salmo salar and Salmo trutta in the greater develop- 
ment of the vomerine teeth, which are persistent throughout 
life, in a long double series on- the shaft of the vomer. About 
seven species are laboriously distinguished by Dr. Gunther 
in the waters of western Europe. Most of these are regarded 
by Dr. Day as varieties of Salmo fario. The latter species, 
the common river-trout or lake-trout of Europe, is found through- 
out northern and central Europe, wherever suitable waters 
occur. It is abundant, gamy, takes the hook readily, and is 
excellent as food. It is more hardy than the different species 
of charr, although from an esthetic point of view it must be 
regarded as inferior to all of the Salvelini. The largest river- 
trout recorded by Dr. Day weighed twenty-one pounds. Such 
large individuals are usually found in lakes in the north, well 
stocked with smaller fishes on which trout may feed. Far- 
ther south, where the surroundings are less favorable to trout- 
life, they become mature at a length of less than a foot, and a 
weight of a few ounces. These excessive variations in the size 
of individuals have received too little notice from students of 
Salmonide. Similar variations occur in all the non-migratory 
species of Salmo and of Salvelinus. Numerous river-trout have 
been recorded from northern Asia, but as yet nothing can be 
definitely stated as to the number of species actually existing. 
The Black-spotted Trout.—In North America only the re- 
gion west of the Mississippi Valley, the streams of southeastern 
