1868.] Mr. 3 .Wood on Variations in Human Myology. 495 



cular septum as far down as the ridge of the internal condyle. The 

 musculo-cutaneous nerve usually passed between the two. The lower slip 

 has been described by the author as a separate element, the coraco- 

 brachialis longus (Journal of Anat. and Phys. No. 1. p. 49). This form of 

 coraco-brachialis is found in the Ornithorhynchus, Echidna, and some 

 Rodents. In the female (No. 30) this long muscle existed in the form of 

 a distinct bundle given off from the middle of the coraco-brachialis, and 

 ending in a long tendon which was implanted fairly upon the inner condyle, 

 and which seemed to originate in a differentiation of the internal brachial 

 ligament. In the female (No. 23) was found a good specimen of the muscle 

 named by the author in the same paper the " coraco-brachialis brevis^'* or 

 " rotator humeri.^'' It arose separately from the under surface of the cora- 

 coid process near its base, and was inserted into the neok of the humerus, 

 just below the lesser tuberosity and above the latissimus dorsi. It is found 

 usually in the Quadrumana, coexistent with the longer form, and in the 

 Rodents and Carnivora singly. 



In the male (No. 9) a large coraco-brachialis gave off a considerable 

 bundle of muscular fibres, which joined bodily those of the brachialis an- 

 ticus. This has been before found by the author, and also by Macwhinnie 

 (op. cit.) and Hyrtl (Lehrbuch, S. 863). It is significant as the homologue 

 of the semimembranosus in the lower extremity, supplying the homologous 

 origin from the coracoid (ischium) as the brachialis supplies the homolo- 

 gous insertion. 



14. Biceps brachii. — In 2 males and 6 females, out of the 36 dissected 

 this session and given in the Table, this muscle was provided with a third 

 or humeral head. In the left arm of No. 14 a slip of muscular fibres was 

 given off from the lower third of the coraco-brachialis ^ and joined the 

 short head about its middle. This seems to be merely a doubled or divided 

 short head, of which the lower portion separates from the coraco-brachialis, 

 lower down than usual, as we frequently find in the Quadrumana. In both 

 arms of No. 17 the muscular slip, half an inch wide, was given off from the 

 humerus just at the insertion of the coraco-brachialis. In the 6 other in- 

 stances the third head arose, in the most usual place, with the upper fibres 

 of the brachialis anticus, and joined the tendon at the same point as the two 

 normal heads. In 1 (No. 24) it was found on both sides, in 4 on the left 

 side only, and in 1 on the right side only. 



Out of 1/5 subjects examined by the author, a third or humeral head of 

 the biceps was found in 14, viz. in 7 males and 7 females. In 4 others, 

 viz. 3 males and 1 female, it was found coexistent with a fourth head, 

 also arising from the humerus. In 3 of these the fourth head arose from 

 one of the tuberosities or the borders of the bicipital groove ; and in the 

 fourth, from the outside of the humerus, between the insertion of the deltoid 

 and the origin of the supinator longus. This gives a proportion of about 1 

 in 9 out of the 175 subjects, agreeing nearly with the computation of Theile, 

 viz. 1 in 8 or 9, and not with that of Hallett, viz. 1 in 15. 



