492 THE ANATOMY OF VERTEBKATED ANIMALS. 



from tlie calcaneiim; the origin of tlie j&bular interosseus 

 of the second digit of the pes from the middle metatarsal, 

 on the dorsal side of the tibial interosseus of the middle 

 digit. The result of the last-mentioned aiTangement is 

 that the second digit of the jDes has two " dorsal " interossei, 

 like the third digit of the manns. In the Apes the interossei 

 of the second digit are generally arranged in the same way 

 in both manus and pes. 



The tendons of the flexor hallucis longus ajid fl,exor digi- 

 toniin perforans are usually more closely connected in the 

 sole of the foot in Man, than in the Anthropomorpha. But 

 it is to be noted that all the apparently distinctive pecu- 

 liarities of the myology of the Anthropomorpha are to be 

 met with, occasionally, as varieties in Man. 



In the brain of Man, the only distinctive features, apart 

 from its absolute size (55 to 115 cubic inches), are the 

 filling-iip of the occipito-temporal fissure; the greater 

 complexity and less symmetry of the other sulci and gyri ; 

 the less excavation of the orbital face of the frontal lobe ; 

 and the larger size of the cerebral hemispheres, as com- 

 pared with the cerebellum and the cerebral nerves. 



There is no diastema, though the summits of the canines 

 project, slightly, beyond the level of the other teeth. The 

 premolars have not more than two roots, and the anterior 

 edge of the crown of the anterior lower premolar is not 

 prolonged and sharp. The permanent canine tooth emerges 

 before the second molar. 



The penis is devoid of a bone (though a prismatic carti- 

 laginous body has occasionally been foiind in the centre of 

 the glans), and its glans has a different shape from that of 

 any of the Anthropomorpha. The vulva looks downwards 

 and forwards, and the clitoris is comparatively small. 



The changes in the proportions of the different parts of 

 the body, at different periods of intra- and extra-uterine 

 life, are very remarkable. In a fcetus an inch and a half 

 long, from the vertex to the heel, the head takes up from 

 one-third to one-fourth of the entire length. The arms and 

 legs are of about the same length, and are shorter than the 



