REPORT ON THE MARSUPIALIA. 19 



into a distinct longitudinal groove, and in this groove are lodged the four fleshy bellies 

 and thread-like tendons of the flexor sublimis. This is the condition of affairs as low 

 down as the lower border of the anterior annular ligament, but here the thick rope-like 

 tendon divides into five parts, and these diverge — one going to each of the five digits. 

 The minute tendons of the sublimis also separate and pass one to each of the four ulnar 

 digits. On the fingers the tendons are arranged in the usual manner. 



In the Thylacine and Phascogale the arrangement of the flexor muscle is very similar. 

 In the former, however, it is to be noted that the condylar portion of the muscle is very 

 much the largest of the three divisions, and also that the ulnar part springs from both 

 bones of the forearm and from the interosseus membrane between them. Further, the 

 four minute tendons of the subhmis have no fleshy bellies, but arise directly from the 

 superficial surface of the rope-like tendon of the profundus. 



The nerve supply of the great flexor muscle shows how thoroughly the fibres of 

 the flexor sublimis and flexor profundus are commingled. Both the ulnar and median 

 nerves send twigs to the condylar and ulnar portions of the muscle, whereas the radial 

 portion derives its nerve-filaments from the median alone. 



The lumbrical muscles are four in number in each of the three animals. They 

 spring from the four ulnar tendons of the flexor profundus, and are inserted one into each 

 of the four ulnar digits. In Thylacinus and Phascogale they are very minute and 

 insignificant, but in Cuscus they are powerfully developed, and expand greatly at their 

 insertions. 



Pronator quadratus. — In Tliylacinus this muscle lies over the lower fourth of the 

 two bones of the forearm ; in Cuscus and Phascogale it covers fully a third of the bones. 

 Compared with other Marsupials, therefore, it may be considered to be poorly develojjed 

 in these three animals. 



Intrinsic Muscles of the Hand. 



By the term intrinsic, as applied to the muscles of the hand, I mean those muscles 

 which remain after the removal of the flexor and extensor tendons. It does not include 

 the lumbricales. 



In the Tliylacine, Cuscus, and Phascogale the intrinsic muscles of the manus may be 

 considered to consist of three groups, viz., (a) a palmar; (b) an intermediate; and (c) a 

 dorsal, according to the plane which they occupy, as we dissect from the palmar to the 

 dorsal aspect of the hand. But further, these three groups have each their own distinctive 

 action upon the fingers with which they are connected, and thus this classification of them 

 is founded, not only upon anatomical but also upon physiological grounds. The palmar 

 group is composed of the adductors of the fingers. The dorsal group consists of the four 

 dorsal interossei, and also of the abductor pollicis and abductor minimi digiti. The two 



