94 Salmonidae 



among the salmon proper only two species, Salmo solar and 

 Salmo tmtta. The latter species, the sea-trout or salmon-trout 

 of England and the estuaries of northern Europe, is similar to 

 the salmon in many respects, but has rather smaller scales, 

 there being fourteen in an oblique series between the adipose 

 fin and the lateral line. It is not so strong a fish as the salmon, 

 nor does it reach so large a size. Although naturally anadro- 

 mous, like the true salmon, landlocked forms of the salmon- 

 trout are not uncommon. These have been usually regarded 

 as different species, while aberrant or intermediate individuals 

 are usually regarded as hybrids. The salmon- trout of Europe 

 have many analogies with the steelhead of the Pacific. 



The present writer has examined many thousands of Ameri- 

 can Salmonida, both of Oncorhynchus and Salmo. While many 

 variations have come to his attention, and he has been com- 

 pelled more than once to modify his views as to specific dis- 

 tinctions, he has never yet seen an individual which he had 

 the slightest reason to regard as a "hybrid." It is certainly 

 illogical to conclude that every specimen which does not corre- 

 spond to our closet-formed definition of its species must therefore 

 be a "hybrid" with some other. There is no evidence worth 

 mentioning, known to me, of extensive hybridization in a state 

 of nature in any group of fishes. This matter is much in need 

 of further study; for what is true of the species in one region, 

 in this regard, may not be true of others. Dr. Gunther observes : 



"Johnson, a correspondent of Willughby, had already ex- 

 pressed his belief that the different salmonoids interbreed; 

 and this view has since been shared by many who have ob- 

 served these fishes in nature. Hybrids between the sewin 

 (Salmo trutta cambricus] and the river-trout (Salmo fario} were 

 numerous in the Rhymney and other rivers of South Wales 

 before salmonoids were almost exterminated by the pollutions 

 allowed to pass into these streams, and so variable in their 

 characters that the passage from one species to the other could 

 be demonstrated in an almost unbroken series, which might 

 induce some naturalists to regard both species as identical. 

 Abundant evidence of a similar character has accumulated, 

 showing the frequent occurrence of hybrids between Salmo 

 fario and S. trutta. ... In some rivers the conditions appear 



