316 Recherches sur les Poissons Fossiles. 



This exposition will serve as a guide to those, who are 

 desirous of becoming acquainted with fossils only, without 

 requiring to enter specially on the study of Ichthyology ; 

 and will explain at the same time, all the proper terms 

 which I have used in the description of species. By this 

 means, I shall be able to afford a better knowledge of 

 the exact characters by which to identify in the different 

 classes of the animal kingdom, those detached parts of the 

 organic bodies which may become the subject of investiga- 

 tion, so that any one of no pretensions will thus be able to 

 distinguish a scale, a bone, or a tooth of fishes, from the cor- 

 responding parts of other animals, which may be found with 

 them. I have also frequently had occasion to remark, how 

 easy it is to mistake some of these fragments amongst 

 themselves ; for example, bones or teeth for scales. 



The skin of which the scales are a special production, de- 

 serves in all animals particular attention ; the study of it has 

 in every way, unfortunately for Zoology, been too much neg- 

 lected ; amidst the Polypes* and the Meduse,j- where it is not 

 yet detached from the mass of the body ; amidst the Echino- 

 dermes% and the Molluscs ,§ where it forms the calcareous 

 shell; amidst the articulated animals,|| in which it forms 

 horny rings, and even in fishes, reptiles, birds, and mammalia, 

 where the lamellar scales, the horny plates, the feathers, 

 and the hair, in all assume a peculiar structure, and pro- 

 duce different solid shapes in each class. 



It is easy to see the reason of all these modifications, 

 destined to protect the body of the animal against the influ- 

 ences of the external world. The skin is but the result of the 

 action and re-action, which is established between the being 

 and medium in which it is enveloped and lives ; and if it be 



* Sea Slugs.— Ed. f Sea Nettles.— Ed. 



X Sea Eggs, Sea Urchins, and Star Fishes.— Ed. § Shell Fish.— Ed. 

 || Insects so called, from the outward covering of their bodies being 

 composed of detached pieces. — Ed, 



