PERIOD OF LINNAEUS. 305 



class of Mammalia, in the tenth edition. In the later 

 editions, however, the Cyclostoms, Plagiostoms, Chimrerae, 

 Sturgeons, Lophioids, Discoboli, Gymnodonts, Scleroderms, 

 and Lophobranch.es are excluded from it, and referred to 

 the class of Eeptiles. The class of Insects, 1 as limited by 

 Linnaeus, embraces not only what are now considered as 

 Insects proper, but also the Myriapods, the Arachnids, 

 and the Crustacea; it corresponds more accurately to the 

 division of Arthropoda of modern systernatists. The class 

 of Worms, the most heterogeneous of all, includes besides 

 all the Radiata or Zoophytes and Mollusks of modern 

 writers, also the Worms, intestinal and free, the Cirripeds, 

 and one Fish (Myxine). It was left for Cuvier 2 to intro- 

 duce order into this chaos. 



Such, with its excellences and short-comings, is the 

 classification which gave a most unexpected and unpre- 

 cented impulse to the study of Zoology. It is useful to 

 remember how lately a performance, even so imperfect, 

 has so greatly influenced the progress of science, in order 

 to understand why it is still possible that so much may 

 remain to be done in systematic Zoology. Nothing, 

 indeed, can be more instructive to the student of Natu- 

 ral History than a careful and minute comparison of the 

 different editions of the " Systema Naturae" of Lin- 

 naeus, and of the works of Cuvier and other prominent 



1 Aristotle divides this group more 3 It would be injustice to Aristotle 



correctly than Linnaeus, as he admits not to mention that he already uuder- 



already two classes (yivii ntyuna) stood the relations of the animals 



among them, the Malacostraca (Crus- unitedintooneclassbyLinna3us,under 



tacea), and the Entoma (Insects), the name of Worms, better than the 



Hist. Anim., Chap. vi. He seems great Swedish naturalist. Speaking, 



also to have understood correctly the for instance, of the great genera or 



natural limits of the classes of Mam- classes, he separates correctly the 



malia and Reptiles, for he distin- Cephalopods from the other Mollusks, 



guishes the Viviparous and Ovipa- under the name of Malakia. Hist, 



rous Quadrupeds, and nowhere con- Aiiim., Lib. I, Chap. vi. 

 founds Fishes with Reptiles. Ibid. 



X 



