1865.] 



Science in Canada. 



523 



Cuvier and De Candolle, which unites in one species all those indi- 

 viduals which so resemble each other that we may reasonably infer 

 that they have descended from a common ancestry. Such a definition 

 is, for practical purposes, unaffected by the Darwinian hypothesis. 

 The origin of the first individuals of a species may be, and probably 

 is, a problem not within the province of natural history. Of vital 

 force, and of creative force or power, we are ignorant. We know 

 nothing, except by inference, of its laws, and' we must always be 

 obliged to pause at the line where what we call force resolves itself 

 into the will of the supreme spiritual Power. The species is a natural, 

 the genus an artificial group ; they differ not in degree, but in kind. 

 There are four distinct grounds on which comparisons may be made 

 for purposes of classification. These are : 1st, intimate structural re- 

 semblance, used in forming genera ; 2nd, grade or rank, as to com- 

 plexity of structure or development of the highest functions, used for 

 distinguishing orders ; 3rd, use or function, referring to special de- 

 velopment of the nervous, motive, nutritive, or reproductive function 

 respectively, enabling us to group animals into classes ; and 4th, plan 

 or type, enabling the naturalist to mark the primary division of ani- 

 mals into provinces. Dr. Dawson adopts Cuvier's fourfold division 

 into Vertebrata, Articulata, Mollusca, and Eadiata, considering it to 

 be by much the most natural and philosophical yet proposed. He re- 

 gards as retrograde the attempts to introduce additional branches or 

 provinces, such as the Protozoa of Siebold, the Ccelenterata of Leuck- 

 art, and the provinces Molluscoida and Annuloida of Huxley. 

 The following is his table of classes : — 





Table 



of Classes of 



Animals. 





Provinces or 

 Branches. 



Vertebrata. 



Articulata. 



Mollusca. 



Radiata. 



j. Nervous class. 



Mammalia. 



Arachnida. 



Cephalopoda. 



Echinodermata 



2. Motive class. 



Aves. 



Insecta. 



Gasteropoda (in- 

 cluding Ptero- 

 poda.) 



Acalephx. 



3. Nutritive class. 



Reptilia. 



Crustacea. 



Lamellibranchiate. 



Antliozoa. 



4. Embryonic or 

 Reproductive 

 class. 



Pisces. 



Annulata, 



Molluscoida (in- 

 cluding Tunicata, 

 Brachiopoda, and 

 Bryozoa). 



Protozoa. 



