VERTEBRATE ZOOLOGY. 469 



the case only in a limited degree, and the group cannot be 

 divided into natural morphological sections distinguished 

 by the habits in question. Two genera may be said to be 

 anadromous i.e., Salmo and Oncorhynchus ; three normal- 

 ly fresh-water i. e., Solar, Salvelinus, and Cristivomer ; and 

 one doubtful i. e., Hypsifario. 



1. The genus Salmo is now restricted to a single species, 

 the common salmon, Salmo salar. Although normally an 

 anadromous type, and refusing to eat even when it ascends 

 fresh-water streams during the breeding season, it neverthe- 

 less is liable to be landlocked ; and when thus excluded,/rom 

 infancy, from access to the sea, it may accommodate itself to 

 the fresh water, and therein increase and multiply, but under 

 such circumstances it never attains the size its anadromous 

 relatives do. 



2. The genus Salar is represented by the common trout 

 of Europe {Salar fario) and a number of related species in 

 the United States. All the American species are confined to 

 the western portions of the continent, and may be recognized 

 by the black dots liberally sprinkled over the back and sides 

 as well as fins. The teeth on the vomer extend quite far 

 backwards. They are characteristic fresh-water fishes. Six 

 species are recognizable i. e., S. irideus (the common Cali- 

 fornian trout), S. tsuppitch, S. spilurus, S. stomias, S. henshaioi, 

 and S. clarhii. 



3. The genus Salvelinus is typified by the chars of Eu- 

 rope, and in this country is manifested in the common trout 

 of the Eastern States and related species found elsewhere. 

 All the American species have red or vermilion spots ; the 

 chief character, however, is the restriction of vomerine teeth 

 to the front of the bone and the immersion of the shaft be- 

 low the surface. The common Eastern species is widely dif- 

 fused, and its proper name is Salvelinus fontinalis. A sec- 

 ond Eastern species is the blue-back of certain Maine lakes, 

 to which it seems to be confined, and from one of which it 

 derives its name Salvelinus oquassa ; this is a very strongly 

 marked form. Much nearer to the S. fontinalis are the S. 

 spectabilis, and especially the S. bairdii of the Pacific slope, 

 and the S. stagnalis, S. rossi, S. hoodi, S. lordi, S. arcturus, 

 S. naresii, and S. tudes of the higher north. 



4. The genus Cristivomer is peculiar to North America, 



