igo FISHES 



These early Australian experiments are interesting as showing the 

 difficulties encountered, and, in the case of brown-trout, the remark- 

 able success which ultimately attended the first introduction into 

 Tasmania. 



The question of the probable merging of various species into one 

 generalised form is an interesting one. Those who have discussed it in 

 the colonies have not perhaps very clear ideas as to what constitute 

 specific distinctions. Indeed one might go further and say that very 

 few biologists have yet attained to clear views on this subject. Most 

 species are founded on structural characters, some of which appear 

 to be very mobile, while physiological characters — ^which may be and 

 often are the dominant factors in differentiation — are extremely 

 difficult to estimate. Thus Salmo salar may be considered to be a 

 distinct species, structurally and physiologically, and though healthy 

 hybrids are readily produced with S. trutta and S. farm, there is no 

 proof that these hybrids are fertile. Indeed the question does not 

 seem to have been tested. On the other hand it seems to me doubtful 

 whether S. trutta and S. fario are distinct species or only varieties 

 of one somewhat variable species. They cross freely, and it is only 

 in reference to this crossing that there has arisen the question of a 

 generalised type occurring in New Zealand. There is no question of 

 the probable crossing of species of Salmo with those of Salvelinus or 

 Onchorhynchus, these latter genera belonging to totally distinct types ; 

 and while their species may be fertile within generic limits, they are 

 not likely to hybridise at any time with species of Salmo. 



Mr A. J. Rutherford considers that the commingling of so many 

 species and varieties of the genus Salmo in our streams will result 

 in the establishment of one generalised type, which, with some dis- 

 regard of the laws of scientific nomenclature and publication, he 

 calls Salmo trutta novee-zealandice. I quote the following passages 

 from a Memorandum (undated) which he furnished to the Otago 

 Society. 



Though these islands lie in the latitude of the Levant, Italy and 

 Switzerland, with widely different ocean surroundings, we introduced 

 various forms of Salmonidae from higher latitudes in the Northern Hemi- 

 sphere, such as the Loch Leven Trout, Scotch Burn Trout, Sea Trout, etc., 

 and fondly imagined that these varieties would retain their characteristics 

 in their altered environment. The fallacy of this idea has been abundantly 

 proved, and after making some slight study of the forms of trout found 

 in the North Italian Lakes, such as Como and Maggiore, I came to the 

 conclusion that they are almost identical with the form of S. trutta novee- 

 zealandiee found in Wakatipu, Wanaka and in South Alpine New Zealand 

 Lakes. The trout in our rivers are also much more akin to the Italian and 

 Swiss varieties than to the British types, and in my opinion it matters little 



