454 



THE MAMMALS 



in this monkey. We call this the rhesus, or shortened to rh, factor ; 

 persons having it are called rh positive ; those not having it called rh 

 negative. It is inherited and a baby that inherits the rh factor from 

 its father may develop a serious blood condition when he has an rh 

 negative mother. 



The Apes. These are the most man-like of all other animals. The 

 arms are considerably longer than the legs, so they walk in a semi- 



Courtesy Chicago Natural History Museum 



Fig. 28.30. Orangutan. Facial expression of the orang is very human-like. They 

 have such long arms that their fingers almost touch the ground when standing upright. 



upright position touching their knuckles to the ground for balance as 

 they go. However, their feet are more adapted for grasping than walk- 

 ing and they walk primarily on the outside edge of the foot. This gives 

 them a characteristic shuffling, bowlegged gait. They do not have a tail 

 as adults but, like man, have an embryonic tail and rudimentary tail ver- 

 tebrae in the adult. 



The gibbons, found in the Malay region, are the smallest and most 

 primitive of the apes. They do not reach a height of more than three 



