THE SALMON FAMILY. 45 
longer head, rather smaller scales, and the dorsal 
fin rather lower than in the northern form (sig- 
nifer); but the constancy of these characters in 
specimens from intermediate localities is yet to be 
proved. It is probable that the grayling once had 
a wider range to the southward than now, and that 
so far as the waters of the United States are con- 
cerned, it is tending towards extinction. This 
tendency is, of course, being accelerated in Michi- 
gan by lumbermen and anglers. The colonies of 
grayling in Michigan and Montana are probably 
remains of a post-glacial fauna. 
' The genus Oxcorhynchus contains those species 
of Salmonide which have the greatest size and 
value. They are in fact, as well as in name, the 
king salmon. The genus is closely related to 
Salmo, with which it agrees in general as to the 
structure of its vomer, and from which it differs in 
the increased number of anal rays, branchiostegals, 
pyloric coeca, and gill-rakers. The character most 
convenient for distinguishing Oncorhynchus, young 
or old, from all the species of Salmo, is the num- 
ber of developed rays in the anal fin. These in 
Oncorhynchus are thirteen to twenty, in Sa/mo nine 
or ten. 
The species of Oxcorhynchus have long been 
known as anadromous salmon, confined to the 
North Pacific. The species were first made known 
one hundred and thirty years ago, by that most 
exact of early observers, Steller, who described and 
distinguished them with perfect accuracy, under 
their Russian vernacular names. These Russian 
names were, in 1792, adopted by Walbaum as 
