1864.] DR. DAWSON ON CLASSIFICATION OF ANIMALS. 255 

 TABLE OF CLASSES OF ANLMALS. 



All of the above groups are recognized by common consent as 

 classes, except a few which have been already incidentally ad- 

 verted to, and to which it is not necessary again to refer here.* 



It will be observed that the order in descending the columns is 

 that of affinity ; that in reading across the columns is the order of 

 analogy. The affinities no naturalist will seriously doubt. The 

 analogies may be less familiar. In examining them, it will be 

 seen that the first class in each province includes animals remark- 

 able for condensation of the head and body, where the former 

 exists ; for high nervous energy, sensation, and intelligence ; for 

 prehensile apparatus, and for absence or simplicity of metamor- 

 phosis. The classes in the second line are characterized by the 

 greatest locomotive powers in their respective provinces ; those in 

 the third line by the development of the nutritive apparatus and 

 of vegetative growth ; those in the fourth line by embryonic char- 

 acters when mature, and by abundant reproductive energy. 



It will be observed also as a necessary consequence of the sys- 

 tem we have pursued, that each of our classes includes animals of 

 very various rank or grade. Indeed, most of them have at their 

 bases forms so simple or imperfect that it is almost impossible to 

 include them in the class-characters. This is no objection to our 

 arrangement, but a proof of its correctness ; for we have now 

 arrived at the point where we must form Orders based solely on 



* The rank given to the Arachnida will be disputed by some naturalists ; 

 but a consideration of the structures of these animals will show that 

 their relations to the insects and the Crustacea are similar to those of the 

 mammals to the birds and the reptiles; and that it is no more reasonable to 

 say that the arachnidans are nearer to the crustaceans than to the insects, 

 on the ground of general structure, than it would be to do the same in 

 the case of the mammals and the reptiles as compared with the birds. 



