ANATOMY OF THE ANTHROPOID APES. 185 



§ 5. Muscular System. 

 As Troglodytes calvus is undoubtedly a distinct species, I have thought it worth 

 while to give such notes upon the muscles as I am able from my dissections of the 

 limbs. The other muscles I have not touched at all. There is no account of the 

 myology of this Chimpanzee, unless it be identical with T. auhryi; but this identifi- 

 cation, as I have already pointed out, is hardly possible. 



§ 6. The Muscular Anatomy of the Fore Limb. 



(1) Pectoralis major. — This muscle has a clavicular origin as in Man ; it is large and 

 powerful and undivided at its insertion, which is two and a half inches in leno-th ; 

 anteriorly a tendinous slip reaches the head of the humerus. The muscle where it is 

 inserted is tendinous on the under surface, but fleshy above ; posteriorly it is inserted 

 in common with a part of the deltoid, this part of the muscle being fleshy on both 

 faces. 



(2) Pectoralis minor. — The stout tendon of insertion of this muscle is upon the 

 coracoid process, just above the origin of the conjoined biceps and coraco-brachialis. 



(3) Subclavius is largely ensheathed by the coraco-clavicular ligament; its fleshy inser- 

 tion is on to the proximal half of the clavicle. 



(4) Coraco-brachialis. — The coraco-brachialis arises, in common with the coracoidal 

 head of the bicejjs, from the coracoid process ; the two muscles become separate at a 

 distance of three inches from their origin ; its insertion measures two inches in length ; 

 near to its insertion some of the fibres of the triceps and of the brachialis anticus 

 arise from it. 



(5) Biceps is composed of two very distinct portions, of which the scapular half is 

 rather, but not very markedly, the thicker ; the two parts of the muscle fuse together 

 about three and a half inches in front of their common insertion; the two halves of 

 the muscle are fleshy where they join. The tendon of insertion measures about two 

 inches up to its beginning on the " coracoid " side of the muscle. It is inserted on to 

 the radius, the diameter at the insertion being three-fifths of an inch. 



(6) Latissimus dorsi. — This muscle gradually narrows towards its insertion, but 

 gets slightly thicker just before it gives off" the dorso-epitrochlear ; it has a diameter 

 of xq inch. The dorso-epitrochlear slip is very large and fleshy ; it ends in a tendon 

 two and a half inches in length, inserted on to the flexor condyle. The insertion of 

 the latissimus dorsi measures one inch in length ; it is completely free from the teres, 

 and there is no division of the muscle into two parts such as occurs in the Orang. 

 The tendon of the muscle commences earlier on its ventral side ; an inch and a half is 

 the length of the completely tendinous part. 



(7) Trapezius. — The insertion of this muscle is on to the external half of the clavicle 

 and on to the greater part of the scapular spine. 



VOL. XIII. — PAET V. No. 2. — February, 1893. 2 e 



