Reclierches sur les Poissons Fossiles. 317 



right to say that the skeleton is, in an animal, a material im- 

 pression of the spirit that has influenced it during its life, 

 we are enabled to affirm also, that the skin is the result of 

 those conditions that exist between the being and the 

 ambient medium. In this point of view, it partakes on the 

 one hand of the nature of the organization of the animal 

 to which it belongs, and on the other, of the conditions of 

 existence in which it is destined to live. It is, then, the field 

 of action to all external influences, and the means by which 

 all the interior actions are transmitted to it without. It is 

 an organ essential to the animal, an external impression of 

 all the peculiarities of its existence, and of its organization, 

 thus carried to the surface, and submitted directly to the 

 view of the observer ; hence from its simple aspect, we are 

 at once enabled at a glimpse to deduce all the details of the 

 structure of an animal which we have never seen, such being 

 the intimate relations which exist between all the organs. 



The study under this point of view will then, as it ad- 

 vances, be found to be of very great importance to com- 

 parative Zoology, and above all, in the examination of fossils 

 of which we find but an external print. 



As the common integuments form the boundary of the se- 

 veral organs, and distinguish at the surface the peculiar 

 forms of animals, before speaking more particularly of the 

 organization of the skin, I should enter here into some de- 

 tails of the general configuration of the body, were I not 

 afraid of departing too far from my subject. I shall merely 

 say, that the figure of any being whatever is determined 

 by the proportions of three dimensions of its bulk, compris- 

 ed under different aspects in different species, 



These dimensions determine also the different regions by 

 which we are in the habit of distinguishing animals. The 

 longitudinal direction establishes the proportions between the 

 anterior and posterior parts, as the head, the breast, the 

 abdomen, and the tail. The breadth we have taken from 



