REPORT ON THE MARSUPIALIA. 17 



These are from the radial to the ulnar aspect of the limb — (1) on the radial border of 

 the lower end of the radius for the tendons of the extensor ossis metacarpi pollicis ; (2) 

 on the dorsal aspect of the radius for the two tendons of the radial extensors ; (3) in the 

 interval between the two bones of the forearm for the tendons of the extensor communis 

 digitorum, and the tendon of the extensor secundi internodii pollicis ; (4) on the dorsal 

 aspect of the lower end of the ulna for the tendon of the extensor minimi digiti or 

 extensor secundus digitorum ; (5) on the ulnar aspect of the ulna for the tendon of the 

 extensor carpi ulnaris. 



In the discus the posterior annular ligament presents seven compartments — (l) on 

 the radial aspect of the wrist for the two tendons of the extensor ossis metacarpi polhcis; 

 (2) on the dorsum of the radius for the supinator longus; (3) on the dorsum of the radius 

 for the tendons of the two radial extensors ; (4) on the dorsum of the radius for the 

 extensor secundi internodii pollicis ; (5) in the interval between the radius and ulna 

 for the tendons of the common extensor and the extensor medii ; (6) on the dorsum of 

 the lower end of the ulna for the extensor minimi digiti ; (7) between the styloid 

 process and the lower end of the ulna for the extensor carpi ulnaris. 



Turning now to the flexor aspect of the forearm, we find the following muscles :— 



1. Pronator radii teres. 4. Flexor carpi ulnaris. 



2. Flexor carpi radialis. 5. Flexores digitorum. 



3. Pabnaris longus. 6. Pronator quadratus. 



Pronator radii teres. — The coronoid head of this muscle is absent in all. In Cuscus 

 and Phascogale the muscle is very strongly developed ; indeed, in the former it is 

 inserted into the greater part of the radial margin of the shaft of the radius, viz., from 

 the supinator brevis above to the root of the styloid process below. In Thylacine it is 

 attached to the middle third of the external border of the radius. 



Flexor carpi radialis. — This muscle is well marked in each of the three animals, and 

 arises, in common with the great flexor muscle of the digits, from the internal condyle of 

 the humerus. In Cuscus its tendon divides into two slips, and these are inserted one 

 into the palmar aspect of the base of the second metacarpal, and the other into the palmar 

 aspect of the base of the third metacarpal bone ; in Thylacine it is inserted partly into 

 the trapezium and partly into the base of the metacarpal bone of the pollex ; and in 

 Phascogale it is inserted into the trapezium alone. 



The insertion of this muscle in Marsupials is somewhat variable. In the Wombat, 

 Phalanger, Opossum, and Bandicoot it is inserted into the base of the second metacarpal ; ' 

 into the metacarpal bone of the pollex 2 in Bennett's Kangaroo ; and into the base of the 

 middle metacarpal in the Koala. 3 



1 Macalister, Ann. and Mag. of Nat. Hist., vol. v., 4th ser., p. 1C2. 



2 Haughton, Proc. Roy. Irish Acad., 1866, p. 479. 



3 Young, Jour. Anat. and Phys., vol. xvi. p. 230. 



(ZOOL. CRALL. EXP. PART XVI. 1882.) Q 3 



