402 THE ANATOMY OF YERTEBKATED ANIMALS. 



raised edges leads from the cardiac eud of the gullet to the 

 middle compartment. 



The caecum, though distinct, is relatively small, and has no 

 vermiform appendage. 



The liver varies much in the degree of its subdivision into 

 lobes, being least divided in the Hemnopitlieci^ and most in 

 the Baboons. The innominate artery generally gives origin 

 to both carotids, as well as to the right subclavian, the left 

 subclavian arisinpr directlv from the arch of the aorta. 



When laryngeal air-sacs are developed, they are not 

 formed by dilatations of the lateral ventricles of the larynx, 

 but a single sac, with a median aperture, is formed in the 

 thyro-hyoidean space immediately beneath the eiDiglottis. 

 This median air-sac is very large, extending down over the 

 front of the neck, and sending processes into the axillge, in 

 some Semnojoitheci and Cynocepliali. The right lung is usu- 

 ally four-lobed, the left two-lobed. 



The kidney has only a single papilla. 



The posterior lobes of the cerebrum project beyond the 

 cerebellum in all the Cynomorpha; they are shortest in the 

 Sem7iopitheci, and longest in the Cynocepliali. The principal 

 sulci and gyri which are found in the human brain are always 

 indicated ; but the external perpendicular fissure is strongly 

 marked. The posterior cornu of the lateral ventricle is large, 

 and there is a strongly-marked Mpjpocamp)us minor. 



There is usually, if not always, a bone in the penis, which 

 is provided with two special retractor muscles. The females 

 are subject to a periodical turgescence of the sexual organs, 

 sometimes accompanied by haemorrhage, and com.parable to 

 menstruation. The placenta is often bilobed. 



h. The Anthropomorplia differ from the (Jynoynorpha in 

 the following characters : They are especially arboreal ani- 

 mals, which habitually assume a semi-erect posture, support- 

 ing the w^eight of the fore-part of the body upon the ends of 

 the fingers, or, more usually, upon the knuckles. There is no 

 tail. The thigh and the leg are, respectively, shorter than 

 the arm and the fore-arm. The dorso-lumbar vertebrae are 

 seventeen or eighteen in number, and their spines are not in- 

 clined toward a common point. They develop no interlocking 

 mammillary and accessory processes. The sacrum contains 

 more than three anchvlosed vertebrsG. The thorax is rather 

 broad than laterally compressed, and the sternum is flattened 

 from before backw^ard, and wide. The axis of the head of the 

 humerus is directed more inward than backward, and the ud- 



