Philosophy of Zoology. 4841 



since the period (1811) when it first became known to me. To the 

 writings of Vicq. d'Azyr I am indebted for the first hints of its 

 existence. Biassed in favour of descriptive anatomy, I have ever ob- 

 jected to the too hasty adoption of extreme transcendental views, 

 holding it to be a true maxim in science, as well as in social life, that 

 the change or step in advance, in order to be certain and trustworthy, 

 must ever be made with caution, and, if possible, supported by the 

 demonstration of physical materials ; or, in other words, the thought 

 which genius submits to the w T orld as an idea must become a physical 

 demonstration before the world can fairly be called on to admit its 

 truth. This is the view I take in the following Memoirs, in some of 

 which it is my intention to apply the transcendental to Natural 

 History as a preliminary to my inquiry into the natural history of 

 man. The true relation of species or race to genus or natural 

 family seemed to me to present a favourable mode of testing the 

 value of the transcendental, not with any idea of testing its truth, — 

 that has been settled long ago, — but of ascertaining its practical 

 value as an instrument of research. The true relation of race to 

 natural family being first discovered, it will then be time enough to 

 apply the transcendental to the relation presumed to subsist between 

 natural families, and, lastly, between these and the universal primaeval 

 life of the organic world of this globe. 



In selecting the natural family of the Salmonidae as a subject of 

 research I have been guided by several considerations : I had already 

 made them the subject of extended research, and their external 

 characters offered favourable points of view for such an inquiry. It 

 is chiefly to the exterior that I give my attention in the present 

 Memoirs ; the interior will follow. I commenced with the dentition, 

 that natural-history character to w r hich all, whether naturalists or 

 anatomists, ascribe such importance ; next followed a brief 

 inquiry into the systems of coloration and proportion. To all 

 these the transcendental applies, or ought to apply, if true. That it 

 is true as a theory I have not a doubt myself, however I may fail in 

 proving it to the satisfaction of others. My immediate object is to 

 prove the existence of a generic animal, the product, no doubt, of 

 hereditary descent from a species, but in itself including the charac- 

 teristics of all the species belonging to that natural family ; or, in other 

 terms, proving hereditary descent to have a relation primarily to genus 

 or natural family. By this term I endeavour to explain family like- 

 nesses commingling with the generic ; the more or less resemblance, 

 for example, of an individual with other affiliated races, to none of 



