656 ON A TRACHYPTERUS FROM N.S.W., 



others having indeed undeniably demonstrated so much, I can 

 not so readily see my way to accepting the suggestion thrown out 

 in the last sentence quoted, since it necessitates an increase in the 

 number of neural spines and a corresponding increase in the 

 vertebrje, in fact a thorough reorganisation of the entire skeletal 

 framework of the fish. I do not know of any instance among the 

 higher forms of animal life where so important a change occurs, 

 and I may be pardoned for doubting its accuracy until some more 

 reliable evidence than has as yet heen brought forward is adduced. 



But, while admitting that these fishes pass through many and 

 puzzling changes in their passage from youth to maturity, and 

 recognising, therefore, the necessity for exercising the greatest 

 caution in dealing with specimens of different ages but from 

 neighbouring localities, it is equally incumbent on us to guard 

 against falling into the opposite error by carelessly uniting 

 together, on such a plea as the above, what may prove to be very 

 distinct species, sooner than trouble ourselves to sift to the bottom 

 every tittle of evidence which we may be able to accumulate; a 

 slovenly habit which, though unworthy of the name of science, is 

 unfortunately altogether too prevalent. 



While, therefore, I am absolutely opposed to the contention of 

 the limited and, I am happy to believe, ever decreasing number 

 of observers who hold that the separation of districts by wide 

 areas of sea and land is no bar to the specific identity of the 

 creatures inhabiting them,* it must he borne in mind that, so far 

 as our present knowledge extends, the conditions which regulate 

 animal life at great depths below the surface of the ocean are 

 everywhere more or less identical, at least so far as temperature, 

 the most important factor affecting the distribution and migration 

 of fishes is concerned; this being so, we know of no obstacle to 

 the cosmopolitan distribution of similar forms. Nevertheless, 

 even here it seems to me that it would be wiser to regard as 



* The union of such species as Squalus acauthias, Glupea sprattus, 

 Engraulis encraskholm, and others with their southern analogues is 'a case 

 in point. 



