EDIBLE FISHES OF QUEENSLAND.— OGILBY. 9 



here to bring about in other directions a habit of body more suitable to the 

 changed conditions under which it now exists. For instance in swiftly flowing 

 mountain torrents a fish with a cylindrical body would offer much less resistance 

 to the current than would one of a deeper and more compressed form, and 

 complies with the primary law which enacts that every natural object shall 

 develop along the line of least resistance ; it is probable that, as in this case, a 

 species, the environment of which had been changed from that of a quiet and 

 comparatively sluggish existence to one of continued and strenuous exertion, 

 should tend to assume a shallower and broader habit as the years roll by. 



(d). "The shorter head." 



In my four specimens the comparative measurements of the length of the 

 head to that of the body are for P. fluviatilis 2-62 to 2-88, for P. colononim 2-55 

 to 2-67. Since, therefore, they are seen to overlap in so small a series, it is evident 

 that little or no reliance can be placed on this character as evidence of specific 

 differentiation. 



(e). "The much more ctenoid character of certain hody-scales in all but older 

 specimens." 

 This claim has also been dealt with above {see p. 2). 



Stead also pointed out that the two forms differed in their habits, but 

 surely that was inevitable in view of their vastly altered conditions of life, and 

 .should carry no weight with it. 



The only other differential character mentioned by Stead (5) is set forth 

 in the following terms : — ' ' The tail too is larger and altogether more powerful 

 than that of the Estuary Perch." With this contention I have dealt under (a). 



In conclusion I assert emphatically that from this re-examination I see 

 nothing to cause me to change my previously expressed opinion, that all the 

 various forms of this fish should be united under the original name — colonorum. 

 There is absolutely no structural character by which P. fluviatilis can be separated 

 from the parent stock while on the other hand every conceivable shade of 

 variation exists, uniting the two forms. P. fluviatilis is doubtless identical with 

 the fish alluded to by me (loc. cit. p. 7) as having been sent to the Australian 

 Museum at my request by Mr. Rose from below the Falls of the Snowy River, 

 and rejected by me as not even worthy of varietal rank. 



None of the authors, who have so overloaded this species with useless 

 synonyms, seem to have taken into account that ov/ing to diversity of environ- 

 ment ; climatic conditions, due not only to their geographical range, but also to 

 the varied altitude at which they may reside; the character of their native 

 streams, whether sluggish and discolored with a muddy or weedy bottom, or clear 

 and sparkling as it flows over a bed of rock and gravel and sand ; the nature of 

 the geographical strata over which the stream flows; the great diversity of the 

 food supply ; and many other fortuitous circumstances, much greater latitude of 

 variation should be allow^ed to fluviatile fishes than to their more equably situated 



