THE SALMON FAMILY. 69 
which are persistent throughout life, in a long 
double series on the shaft of the vomer. About 
seven species are laboriously distinguished by Dr. 
Giinther, 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 
throughout northern and central Europe, wher- 
ever 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 indi- 
viduals are usually found in lakes in the north, 
well stocked with smaller fishes on which trout 
may feed. Farther 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. 
In North America, only the region west of the 
Mississippi Valley, and the valley of Mackenzie 
River, have species of black-spotted trout. If we 
are to follow the usage of the names “salmon” 
and “trout,” which prevails in England, we should 
