MAY, 1921. AMERICAN MARSUPIAL, C^NOLESTES OSGOOD. 47 



There is also an abductor of the index digit which is separately de- 

 scribed owing to its more palmar position than the other interossei. 



The abductor pollicis is a short thick muscle with origin from the 

 trapezium, the transverse ligament and the base of the first metacarpal. 

 Its insertion is on the radial side of the distal extremity of the first 

 metacarpal. 



The abductor digiti minimi also is a relatively large muscle. It orig- 

 inates on the pisiform bone opposite the insertion of the flexor carpi 

 ulnaris and inserts by a flattened tendon running under the annular 

 ligament to the outer side of the metacarpo-phalangeal joint of the fifth 

 finger. 



The abductor digiti indicis arises on the trapezium and the base of the 

 first metacarpal and inserts near the distal end and on the radial side of 

 the second phalanx in close apposition with the short flexor. It is in 

 nearly the same plane as the flexors and is visible alongside the abductor 

 pollicis before removal of the large tendons. It is also visible from the 

 dorsal aspect of the hand. 



Excluding the above described abductor indicis, there are three 

 dorsal interosseus muscles. These lie over the spaces between the four 

 outer metacarpals, are almost wholly dorsal in position, and resemble 

 those described and figured for Phalanger (Cuscus) by Cunningham 

 (loc. cit., p. 23, pi. II, fig. 2) . The one between the index and the medius 

 has origin principally on the ulnar base and side of the second metacarpal 

 and insertion with the tendon of the short flexor on the radial side of the 

 third metacarpal. That between the medius and the annularis arises 

 from the bases and the sides of the third and fourth metacarpals and 

 inserts on the tendon of the short flexor on the ulnar side of the third 

 metacarpal. That between the annularis and minimus arises from the 

 bases and sides of the fourth and fifth metacarpals and inserts on the 

 tendon of the short flexor of the ulnar side of the fourth metacarpal, also 

 sending a short tendinous slip to the radial side of the fifth metacarpal. 



MUSCLES OF THE HIND LIMB. 

 Plates V-VI. 



Adductor longus. Origin from the side of the ramus of the ischium 

 from the symphysis pubis to the insertion of the semimembranosus. 

 Its origin is ectad of the adductor magnus and entad of the gracilis. Its 

 caudal border parallels the semimembranosus. Insertion on the inner 

 condyle of the femur and the inner side of the head of the tibia. 



Adductor magnus. Origin from the side of the pubic symphysis and 

 thence dorso-craniad along the edge of the pubis to the middle of the 



