CHAP. IV] THE GENERAL ANATOMY OF GORILLA 179 



condition in the Orang, Hylobates and in the Cercopithecidae) to 

 form the scaphoid bone of the wrist. 



The sternum is flat (latisternal) and the junction of pre- 

 and meso-sternum occurs at the level of the third costal cartilage 

 more commonly than in Man, but less usually than in Hylobates. 



The following numerical data are taken from Aeby's work on 

 the Osteology of the Gorilla 1 . 



Proportions of the several segments of the limbs : 

 Upper limb: Arm 411%. Forearm 32*7%. Hand 26"2%. 

 Lower limb: Thigh 41-3%. Leg 30-5%. Foot 28-2%. 



F. Muscular System-. The muscular system now claims 

 attention and will be considered in the same way as in the 

 accounts of the Lemuroidea, the Tarsii and the Cercopithecidae. 



The muscles correspond severally with very close accuracy to 

 those of Man, and in fact the number of distinctive human muscles, 

 at one time thought to be thirteen, is now reduced to three (M. 

 plantaris, peroneus tertius and serratus posticus inferior). The 

 acromio-trachelian and dorsi-epitrochlear muscles distinguish the 

 Gorilla, not being normal in Man. 



While a general agreement in the individual muscles exists, 

 there is a definite distinction to be drawn as regards their rela- 

 tive development in Man and in the Anthropoid Apes. Thus while 

 Man is characterized by the development of the musculature 

 of the lower limb, in the Gorilla that of the upper limb has been 

 developed. The musculature of the upper limb bears to that of 



the lower limb the proportion of by weight in the Orang-utan 



(the proportion in the Gorilla will be about the same), while the 



proportion in Man is ^ . At the same time, when the upper limbs 



o 



of the Gorilla and Man are compared, it will be seen that in the 

 Gorilla the extensor series of muscles falls far behind that of Man in 

 relative development (16% instead of 22% of the total musculature 3 ). 



1 Morphologisches Jahrbuch, Band iv. 



s See the bibliography published by Keith in Natural Science, 1897. Also 

 Kohlbrugge, 1896 op. tit. More recently, Sommer has published an important 

 paper in the Jenaische Zeitschrift, Band xlii. S. 181. 



3 Langer, Sitz. der k. k. Akad. tier Wiss. Wien, Band lxxix. Abth. 3. SS. 

 177 et seq. 



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