Chap. III. PERIOD OF CUVIER. 195 



When we consider the zoological systems of the past century, that of Lin- 

 naeus, for instance, and compare them with more recent ones, that of Cuvier, for 

 example, we cannot overlook the fact, that even when discoveries have added little 

 to our knowledge, the subject is treated in a difterent manner ; not merely in 

 consequence of the more extensive information respecting the internal structure of 

 animals, but also respecting the gradation of the higher groups. 



Linnajus had no divisions of a higher order than classes. Cuvier introduced, 

 for the first time, four great divisions, which he called '■'■ embranchemens" or branches, 

 under which he arranged his classes, of which he admitted three times as many as 

 Linnreus had done. 



Again, Linmeus divides his classes into orders ; next, he introduces genera, and 

 finally, species; and this he does systematically in the same gi'adation through all 

 classes, so that each of his six classes is subdivided into orders, and these into 

 genera with their species. Of families, as now understood, Linnaeus knows nothing. 



The classification of Cuvier presents no such regularity in its framework. In 

 some classes he proceeds, immediately after presenting their characteristics, to the 

 enumeration of the genera they contain, without grouping them either into orders 

 or families. In other classes, he admits orders under the head of the class, and 

 then proceeds to the charactei'istics of the genera, while in others still, he admits 

 under the class not only orders and families, placing alwaj^s the family in a sub- 

 ordinate position to the order, but also a number of secondary divisions which 

 he calls sections, divisions, tribes, etc., before he reaches the genera and species. 

 With reference to the genera again, we find marked discrepancies in different 

 classes. Sometimes a genus is to him an extensive group of species, widely differ- 

 ing one from the other, and of such genera he speaks as " grands genres ; " others 

 are limited in their extent, and contain homogeneous species without farther sub- 

 divisions, while still others are subdivided into what he calls sub-genera, and this 

 is usually the case with his " great genera." 



The gradation of divisions with Cuvier varies then with his clas.ses, some classes 

 containing only genera and species, and neither orders nor families nor any other 

 subdivision. Others contain orders, families, and genera, and besides these, a variety 

 of subdivisions of the most diversified extent and significance. This remarkable 

 inequality between all the divisions of Cuvier is, no doubt, partly owing to the 

 state of Zoology and of zoological museums at the time he wrote, and to his 

 determination to admit into his work only such representatives of the animal 

 kingdom as he could to a greater or less extent examine anatomically for him- 

 self; but it is also partly to be a.scribed to his conviction, often expressed, that 

 there is no such vmiformity or regular serial gradation among animals as many 

 naturalists attempted to introduce into their classifications. 



