THE TALE OF THE FISHES 



like the familiar forms of the present age, were spread 

 over the Northern Hemisphere, the smelt and salmon 

 swarming up the rivers as we see them to-day — the 

 male salmon putting on the hooked lower jaw in the 

 breeding season, a provision of nature, by the way, to 

 prevent him from picking up the eggs of the female 

 fish as fast as they are deposited, and for safeguarding 

 her from caesarian section by his sharp teeth when he 

 squeezes her abdomen with his jaws to facilitate the 

 extrusion of the eggs. 



All this is inferred from a few detached fragments 

 which it would be uninteresting to exhibit. The bones 

 of this family being imperfectly ossified and easily de- 

 stroyed, fossil remains of salmonids are rare. 



From these Pleistocene ancestors, we can readily 

 follow the lines of evolution with their diverging forms 

 as indicated in the diagram of the Family Tree. 



The salmon separated into the Atlantic and Paci- 

 fic forms, differing morphologically in the number of 

 anal fin rays, the Pacific Oncorhynchus probably, as at 

 the present day, paying the death penalty for his first 

 and only sexual pleasure. The trout divided and 

 subdivided as I have already described. While you 



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