STRUCTURE OF THE VERTEBRATES 



81 



are used for dissection in most courses in anatomy, are included 

 first. 



Order Insectivora. This order was the first to appear in the 

 evolution of the placentals, and is still the most primitive order. 

 Externally they have numerous specializations, for example: the 

 spines of the European hedge-hog, the jumping habits of the 

 African shrews, and the blindness and digging claws of the 

 moles. Their teeth are very generalized and adapted for insect 

 eating. One family (often set up as a separate order) appears 



Cebus (American Primate) 



American Monkey (Primates) 

 a thumbless, arboreal form 



Fig. 30. Order Primates. The Lemurs (top) are the most primitive mem- 

 bers of the order. The American monkej^s are an early branch from the 



parent stem. 



about mid-way between the insectivores and the most primi- 

 tive primates in several characters. 



Order Primates. The primates are the lemurs, monkeys, apes 

 and man; and a few less well known families. They evolved 

 from the insectivores and are therefore one of the oldest orders 

 of mammals. Most of them are arboreal in habit, and all of 

 them show unmistakable specializations for tree living condi- 

 tions. Man is the least adapted for this ancestral type of life. 

 Tl>e order is divided into the following sub-orders. 



