ME. F. DAT OX BRITISH SALMONES. 405 



number of cseeal appendages is no more a criterion of species 

 than are tlie number of tbe vertebrae. Had tbese New-Zealand 

 examples been submitted to Dr. Giiuther prior to 1865, they 

 Avould undoubtedly have formed at least another new species for 

 the British-Museum Catalogue ; while his riews, as given in his 

 late work, appear to have undergone but little, if any, modifi- 

 cation*. 



Respecting tbe form of the preopercle, the size of the head, 

 and the dentition, wide differences exist in this fish, iu accordance 

 Avith age, sex, and other causes, and A\hich do not call for a 

 detailed examination in this place. I will therefore pass ou to 

 variations in colour — first, internally, and, secondly, externally. 



The flesh of trout may be of a red or of a white tint, due, it 

 has been frequently shown, to the food wliich the fish consumes. 

 And this difference in the food may be consequent either on 

 necessity or choice. Thus, in one river, as at Alresford in 

 Hampshire, crustaceans may be obtained in the loAver portion of 

 the stream, not so in the upper ; in the former the cooked fish 

 cuts pink, in the latter nearly white. It would also appear that, 

 even if the necessary food for occasioning the pink appearance is 

 present it does not follow that the fish selects it, as there are 

 rivers in which some of the brook-trout are red while the others 

 are white, both forms being in good condition and equally excel- 

 lent when served at table. Eeverting to the BaJmofontinaUs, or 

 American charr,Avhich undergoes the same cbanges in this country 

 as S.fario does in Ncav Zealand, what do we find ? The young, as 

 I observed, have been turned out and acclimatized here, and A\-ith 

 the following result as regards this question. Those Avhieh have 

 been liberated in the streams in Cardiganshire are, as food, 

 observes Sir P. Pryse, " very good, the flesh having a peculiar 

 gamboge colour, and rich;" Avhile Mr. Francis Francis tells us, 

 respecting others from Sir James Maitland's, in Perthshire, that 

 their condition left nothing to be desired : they Avere fat and firm ; 

 the flesh was of a beautiful pearly Avhite (' Field,' March 11th, 

 1882). A subsequent correspondent (Coracle, 'Field,' March 

 18th, 1882) states that he has also seen it in this fish perfectly 



* It is difficult to admit that all nuu-migi-atorj trout not agreeing in their 

 flu-formula, their number of vertebra), and coEical appendages with the descrip* 

 tions given in the British-Museum Catalogue, are to be termed hybrids. It 

 seems more rational to surmise that Nature's limits of variation are more exten* 

 sive than those admitted by Dr. Giiuther. 



