BY R. M. JOHNSTOX, F.L.S. 35 



southerly shores of the Southern Island the progeny of the 

 normal type of the European Salmo Srt7ar might find tolerably 

 suitable conditions as regards temperature. Observation, 

 however, discloses the important fact that the only type of 

 migratory salmonoid found in their seas corresponds in all 

 respects with that of the Derwent. 



The only conclusions left to us, therefore, so far as I can 

 judge, are : — either that the assumed wanderers have lost them- 

 selves in the wilderness of waters in the direction of the 

 South Pole, or — that many of the variable types of salmonoids 

 now inhabiting the Derwent are in reality the actual descend- 

 ants of the Salmo solar of Europe, modified by the combined 

 influences of retarded incubation in transit, and the varying 

 <3onditious of their new environment. 



MODIFICATION DUE TO ENVIRONMFNT, ETC, 



To assume, as a last resource, that arrested incubation, 

 together with the changed condition of a new environment, 

 may have modified some of the few remaining characters 

 (such as the size of scales, relative size of maxillary and 

 snout), which in European waters now alone serve satisfactorily 

 to distinguish Salmo salar from some of the larger protean 

 forms of S. trntta, is not so extravagant a notion that it may 

 be dismissed without thoughtful en(|uiry. 



If, on the one hand, the lack of special knowledge on the 

 part of practical fishermen and i)isciculturists frequently lead 

 them to ignore important although variable characters (often 

 hidden to common-sense appreciation), which distinguish 

 closely allied forms ; yet it must be confessed that naturalists 

 in dealing with a protean genus having a wide range of 

 variability, may have a tendency to err at times in seizing 

 arbitrarily upon certain extreme types, and upon these base a 

 classification of a complicated nature, which may serve some 

 useful purpose in grouping the few specimens preserved in 

 Museums, but which may be of little j^ractical value in 

 classifying the myriads of intermediate or overlapping forms 

 captured and sold in the fish markets. Classifiers in 

 Museums may easily resort to the theory of hybridism for 

 labelling the few perplexing intermediate or overlapping forms 

 which find their way to Museum collections ; but what 

 resources have the fishmonger and purchaser when such forms 

 are brought in large numbers to market. Take, for example, 

 the many examples of large-si/.cd silvery forms of suhnon 

 caught in salt watci-, whose maxillary largely exceeds the 

 length of snout, and whose transverse series of scales between 

 root of adipose fin and lateral line exceeds 11 in number. Arc 

 these forms sold as real salmon or as salmon trout ? If wo 

 ■examine the fish stalls, or (juestion the pisciculturist or fish- 



