246 



PRINCIPLES OF ANIMAL BIOLOGY 



now placed in widely separated categories. One genus was erected to 

 include certain sea cucumbers, a worm, a colonial jellyfish, and several 

 primitive near vertebrates ; some of these are now placed near the bottom, 

 others near the top, of the animal scale. 



Later Temporary Systems of Classification. — Following Linnaeus, 

 many naturalists concerned themselves with systematic zoology. Some 

 of them adopted the Linnaean system in general but altered it to suit their 

 tastes, sometimes improving it but quite as often not. Others invented 

 new classifications. Georges Cuvier (1769-1832) established four major 



Fig. 205. — Carolus Linnaeus, 



1707-1778, at the age of forty. 

 Botanical Garden.) 



{Courtesy of New York 



groups, called branches, which he divided into classes, 19 in number; 

 and some parts of his classification remained in vogue in his own country 

 (France) for three-quarters of a century. De Blainville (1777-1850) in 

 several instances happily discovered the structural characters that were 

 of genuine importance in distinguishing natural groups. He proposed a 

 classification involving three subkingdoms, distinguished by the arrange- 

 ment of their parts about a center or axis. These subkingdoms weie the 

 Artiomorphes, having a bilateral form like the majority of animals; the 

 Adinomorphes, with a radiate form like a starfish; and Heteromorphes, 

 animals having an irregular form (chiefly protozoa and sponges). 

 Lamarck (1744-1829) devised a classification based upon nervous sensi- 

 bility and proposed three principal groups: the apathetic animals, those 

 without nervous systems or apparent sensation among the invertebrates; 



