CHAP. IV] THE GENERAL ANATOMY OF GORILLA 177 



would be inadequate to the task of supporting the weight of the 

 head and of the upper limbs, were not the latter still employed as 

 supports and thus as a means of relieving the strain borne entirely 

 by the vertebral column in the human type. 



The pelvis is much more elongated in the cranio-caudal direc- 

 tion than is the case in the human skeleton. The iliac crests are 

 more sinuous, and the iliac fossae more hollow than in any other 

 anthropoid ape, though less so than in Man, and an anterior inferior 

 iliac spine is sometimes found (cf. Chapter xn). The posterior parts 

 of the ilia are less developed and the ischial tuberosities are 

 less massive than in Man. The Os innominatum is long, and 

 deficient in iliac breadth when compared with the correspond- 

 ing human bone. The pelvic brim is, relatively to its sagittal 

 diameter, much narrower than that of Man. Yet in general, 

 the pelvis offers a good demonstration of the modifications 

 necessary for the conversion of this skeletal element from the 

 pronograde type of the lower Primates to the orthograde human 

 type. But the changes are approaching completion in the Gorilla, 

 for this animal presents a pelvis of aspect more nearly human than 

 any other ape can provide. Similar conclusions are to be drawn 

 from the bones of the limb-girdles, limbs and thorax. A few 

 supplementary details will now be added. 



The femur is short, stout, and straight ; the shaft entirely lacks 

 the linea aspera which is so characteristic of the human femur, 

 being flattened sagittally. The neck is short, and the articular 

 surface of the head less extensive than in Man. It makes an 

 angle of about 124° with the shaft. In Man this angle varies 

 from 128° — 141°. As in Man (but unlike the condition in the 

 Orang-utan), the ligamentum teres is found. In the knee-joint 

 the external cartilage is annular, not semi-lunar (cf. Fig. 119). On 

 the tibia no soleal line is seen, and the plane of articulation with 

 the astragalus is very oblique. The fibula is very slender and its 

 malleolus small. The calcaneum is longer and larger than in the 

 other Simiidae, but even thus it falls far behind that of Man in 

 these respects. The first metatarso-tarsal articulation is clearly 

 a ginglymus joint, and contrasts strongly with that of Man, 

 the difference being evidently referable to functional adap- 

 tation. 



d. m. 12 



