1898.] ANATOMY OF PEDETES CAfFER. 887 



of communication between the descendens hypoglossi and the upper 

 cervical nerves is always present in the Eabbit, I only wish to record 

 that I failed to find it in this specimen of Pedetes ; I may have cut 

 it away or this may have been an abnormal specimen. 



Brachial Plexus. — There is reason to believe that the limb plexuses 

 of mammals nearly related differ not only in their arrangement 

 but also in the number of spinal nerves which go to form them. 

 I am led to this belief from the fact that in 1887 Professor Paterson 

 figured the limb plexuses of Atlierura fasciculata (Journal of 

 Anatomy, vol. xxi. p. 611). In 1894 I figured those of Atherura 

 africana (P. Z. S. 1894, pp. 688 & 690). At that time I had 

 not read Prof. Paterson's paper, so that the two observations were 

 quite independent of one another. In my animal the fifth cervical 

 nerve certainly entered into the brachial plexus, while in Prof. 

 Paterson's it was quite independent of it. It seems therefore impor- 

 tant to figure or describe limb plexuses whenever possible in order 

 to find out how far they are constant structures. In Pedetes the 

 brachial plexus is made up of the 5th, 6th, 7th, and 8th cervical nerves 

 and the 1 st thoracic. The 5th and 6th nerves unite to form the 

 outer cord, and it is interesting to notice that this cord receives 

 no communication of any kind from the 7th. 



The 7th and 8th cervical and 1st thoracic nerves unite to form 

 the inner cord, while the posterior cord is made up of fibres derived 

 from all the roots entering the plexus. 



The suprascapular nerve rises from the 5th cervical nerve only ; 

 in Paterson's specimen of Atherura it came from the 6th, while 

 in my specimen of the same animal it came from the 5th, with a 

 smaU branch from the 6th. My own observations make me believe 

 that the 5th cervical is its usual origin in mammals. 



The nerve to the subscapularis (upper subscapular) comes from 

 the junction of the 5th and 6th cervicals. 



The musculo-cutaneous nerve rises from the outer cord, passes 

 above the coraco-brachialis (between it and the humerus) and 

 supplies it ; then it gives off two branches to the flexor brevis 

 cubiti (brachialis anticus), and one to the flexor longus cubiti 

 (biceps) ; after this it becomes cutaneous in the forearm as usual. 



The median nerve rises by a head from the inner and one from 

 the outer cord ; these unite in the axilla and the nerve runs down 

 the arm on the outer side of the brachial artery, with which it passes 

 through the fibrous supracondylar foramen. At the bend of the 

 elbow a bundle of branches is given off which supplies all the 

 muscles of the flexor surface of the forearm except the flexor carpi 

 ulnaris and the flexor sublimis digitorum; the deepest of these 

 branches, the one supplying the pronator quadratus, corresponds 

 to the human anterior interosseous nerve. A little lower down a 

 cutaneous branch is given off which supplies the lower part of the 

 flexor surface of the forearm and the palm. About the middle of 

 the forearm the nerve divides into two branches of equal size, which 

 run side by side with the median artery to the hand : the more 

 ulnar of these is the larger and supplies all four digital clefts as 

 well as the radial side of the poUex and the ulnar side of the 



