246 Agassi? 1 Contributions to the 



therefore their highest perfection ; the Polypi, Acephala and Worms 

 are respectively at the lowest or simplest portion of each branch. 

 Secondly, it is manifest that the three highest classes have each 

 a special reference to the highest development of the psychical 

 powers of the branch, and of its organs of sense and ner- 

 vous system. The three middle classes represent the highest 

 adaptation of the type to variety of locomotion and habitat. The 

 three lowest classes represent the modification of the type 

 with especial reference to the highest development of the mere 

 vegetative life. Class, then, represents the expression of the ge- 

 neral intention of the Creator in the construction of the members 

 of a branch. Ways and means, or combinations of organs, are 

 the indications of that intention which we most readily perceive. 

 In this limited sense we are quite willing to accept the definition 

 of our author. 



In the ordinary division of the vertebrates, even the popular 

 mind, we think, has all along recognised this principle. The 

 Mammal, the Bird, the Reptile and the Fish, differ not merely in 

 structure ; but the first is the expression of the Vertebrate type in 

 relation to its highest psychical powers, the second in relation to 

 extent of locomotive powers, the third and fourth in relation to 

 mere vegetative life in air and in water respectively. 



3. Orders have been fruitful causes of difference among natu- 

 ralists. The ground on which they should stand is thus stated : 



" To find out the natural characters of orders from that which 

 really exists in nature, I have considered attentively the different 

 systems of Zoology in which orders are admitted and apparently 

 considered with more care than elsewhere, and in particular the 

 Sy sterna Natural of Linnaeus, who firs,t introduced in Zoology 

 that kind of groups, and the works of Cuvier, in which orders 

 are frequently characterised with unusual precision, and it has 

 appeared to me that the leading idea prevailing everywhere res- 

 pecting orders, where these groups are not admitted at random, 

 is that of a definite rank among them, the desire to determine the 

 relative standing of these divisions, to ascertain their relative 

 superiority or inferiority, as the same order, adopted to designate 

 them, already implies. The first order in the first class of the 

 animal kingdom, according to the classification of Linnseus, is 

 called by him Primates, expressing, no doubt, his conviction that 

 these beings, among which Man is included, rank uppermost in 

 .their class. Blainville uses here and there the expression of 



