LIBRARY 



THE OTTAWA NATURALIST>t « V^ 



Vol. XII. Ottawa, October AND November, 1898. N0S.7 & 8. 

 CHANGE OF FUNCTION IN FISHES' FlNS. 



By Professor E. E. Prince, 

 Dominion Commissioner of Fisheries, Ottawa. 



In the Ottawa Naturalist, of October last year, a book 

 notice appeared of the nature of a brief review of that highly 

 interesting subject the life-histories of fishes. It included 

 amongst other new and important statements the affirmation 

 that in young fishes " the breast fins, and in some species the 

 hind pair of fins, become enormously developed, and project 

 like wide-spread fans from the sides of the body. These, no 

 doubt, are effective for protection rather than locomotion." 

 Having watched young fishes half an inch to one or two inches 

 in length, when schooling at the surface of the sea in calm sum- 

 mer weather, I have repeatedly noticed that the enormous paired 

 fins, often deeply coloured, black and white in the Rockling 

 {Motelld), orange red in the Gurnard (Trzgla), ochre yellow in 

 the Ling {Molva), or gleaming white in the American Hake 

 {Phycis), are of little or no use in outward locomotion : but hang 

 helplessly by the side of the body. Projecting like richly tinted 

 fans when expanded, or like stout spines and rods when closed, 

 they must effectively deter many emenies eager to make a 

 mouthful of the tender young fish ; and thus serve a purpose 

 similar to the points and projections of caterpillars or the spines 

 of the porcupine, and the like. As I ventured to point out 

 many years ago, the theory put forward by Dr. Albert Gunther, 

 of the British Museum, that they were simply instrumental in 

 balancing the fish is wholly inadequate, and certainly a large 

 number of minute larval fishes {e.g., the cod and mackerel), 

 which would appear to need them most, do not possess these 

 large (supposed) balancing organs. 



