176 On the Classification of Mammalia. 



other the families which have no proboscis. The proboscidians 

 are relatively inferior to nonproboscidians, inasmuch as they 

 are edentata in the general sense of the word : grinding teeth 

 and tusks alone exist. In the nonproboscidians the dental 

 system acquires a great development, the greatest to be ob- 

 served in the edentated trunk ; but as this development is 

 an excessive effort, and thus brought the group beyond its 

 circle of activity, it had only a temporary existence, and be- 

 came almost extinct in the present era. 



The history of pachyderms will form a contrasting episode 

 compared to that of Cetacea, when it shall once be written 

 out fully. Our hypothetical views on the subject, for fear 

 that they should appear too premature, we abstain from giv- 

 ing now. 



§ 7. As to the limits of the order of Ruminantia, every 

 one is agreed ; but not so with regard to its systematic posi- 

 tion. Considering its imperfect dental system, we see that 

 it belongs to the great division of edentated mammals. That 

 ruminants are inferior in rank to rodents, we derive first from 

 their appertaining to the edentated division, which we have 

 seen is inferior to the division of marsupials. Their dentition 

 and herbaceous diet is a second very important feature which 

 assigns to them a lower rank than to the rodents, which feed 

 chiefly on bark and fruits, a food superior to grass and leaves. 



| 8. Now the position of the order Rodentia is clearly de- 

 fined by what has just been said of the ruminants. Their 

 complete system of dentition, and the similarity in the in- 

 sertion of the incisors in herbivorous marsupials, are the 

 reasons which have guided us in this arrangement. 



§ 9. The place which we assign to the order of Insectivora 

 is based upon a similar principle : the affinity of their denti- 

 tion and mode of life with the insectivorous marsupials and 

 edentata. 



§ 10. Pinnipedia have always been placed below Carni- 

 vora, and Carnivora have always been divided into digiti- 

 grada and plantigrada. We find both plantigrada and digiti- 

 grada synthetically indicated in Pinnipedia ; not in the struc- 

 ture of the locomotive members, but in the profile of the face. 

 § 11. In the eccentric groups of Bradipodidai, Sriurida j , 



