PREFACE TO THE FIRST EDITION. IX 



The classes and orders were not only not sufficiently con- 

 formed to the intimate nature of animals to serve conve- 

 niently as a basis to a treatise on comparative anatomy, but 

 the genera themselves, although mostly better constituted, 

 presented but inadequate resources, on account of the species 

 not having been arranged under each of them, in conformity 

 with these characters. Thus in placing the Sea-cow (Mana- 

 tus, Cuv.) in the genus Morse (Trichechus, Lin.), the Siren 

 in that of the Eels, Gmeliu had rendered any general propo- 

 sition relative to the organization of these two genera imposs- 

 ible, just as by approximating to the same class the same 

 order, and placing side by side the Sepia and the fresh- 

 water Polypus, he had made it impossible to say any thing in 

 general on the class and order wiiich embraced such different 

 beings. 



The examples above cited are selected from the most strik- 

 ing of these errors ; but there existed an infinitude of them, 

 less sensible at the first glance, which presented difficulties 

 not less real. 



It was not enough then to have imagined a new ar'^ange- 

 ment of classes and orders, and to have properly placed the 

 genera there ; it was also necessary to examine all the species 

 in order to be assured, whether they really belonged to the 

 genera in which they had been placed. 



Having come to this, I found species not only grouped or 

 dispersed, against all semblance of reason, but I remarked 

 that several had not been positively determined ; neither by 

 the characters assigned to them, nor by their figures and de- 

 scriptions. 



Here, one of them, by means of synonymes, represents seve- 

 ral in one single name, and often so different from each other 

 that they should not be placed in the same genus ; there, a 

 single one is doubled, trebled, and successively reappears in 

 several subgenera, genera, and sometimes in different orders. 



What shall we say, for instance, of the Trichechus mana- 

 tus of Gmelin, which in one single specific name comprises 

 three species and two genera ; two genera, differing in almost 

 Vol. I. (2) 



