IN NATURAL HISTORY. 7 



in this classification of Linna3us ; his class of 

 Worms, also, was most heterogeneous, for he 

 included among them Shell-Fishes, Slugs, Star- 

 Fishes, Sea-Urchins, Corals, and other animals 

 that bear no relation whatever to the class of 

 Worms as now defined. 



But whatever its defects, the classification of 

 Linnaeus was the first attempt at grouping ani- 

 mals together according to certain common struc- 

 tural characters. His followers and pupils en- 

 gaged at once in a scrutiny of the differences 

 and similarities among animals, which soon led 

 to a great increase in the number of classes ; in- 

 stead of six, there were presently nine, twelve, 

 and more. But till Cuvier's time there was no 

 great principle of classification. Facts were ac- 

 cumulated and more or less systematized, but 

 they were not yet arranged according to law ; 

 the principle was still wanting by which to gen- 

 eralize them and give meaning and vitality to the 

 whole. It was Cuvier who found the key. He 

 himself tells us how he first began, in his investi- 

 gations upon the internal organization of animals, 

 to use his dissections with reference to finding the 

 true relations between animals, and how ever 

 after his knowledge of anatomy assisted him in 

 his classifications, while his classifications threw 

 new light again on his anatomical investigations, 

 each science thus helping to fertilize the other. 



