CHAP. IV] THE GENERAL ANATOMY OF THE CERCOPITHECIDAE 147 



The latter may be the fourteenth thoracic in these animals. 

 Thymic remains are visible on the anterior aspect of the peri- 

 cardium, which is also crossed by the right phrenic nerve. 



Upper lobe 



^ ^ N :\ 



-Middle lobe 



Recess in pleural cavity 

 for Lobus azygos 



- Heart 



Diaphragm 



"Lobus azygos 



Fig. 91. Lateral aspect of the right lung of a Cercopithecus monkey (Cerco- 

 pithecidae) to shew the lobus azygos impar. 



Upper lobe - 



Lower lobe 



Fig. 92. Lateral aspect of the left lung of a Cercopithecus monkey (Cerco- 

 pithecidae). The heart is also shewn. The lung is divided into three lobes, thus 

 differing from the human lung of the left side, while resembling the right human 

 lung. 



J. Alimentary System. Sections of the lips of a Cynoce- 

 phalous monkey (Fig. 93) shew that the M. orbicularis oris is met 

 with in cross-section, and extends thus as an attenuated band to 

 the free margin of the lip, where it is slightly recurved. Mucous 

 glands are abundant here, as also around the entrance to the 

 cheek-pouch. The M. buccinator is spread out over the wall of 

 the latter and indeed is pulled downwards as it follows the neck 



10—2 



