12 



MR. E. J. SIDEBUTHAM ON THE 



[Jan. 20, 



Third dorsal interosseous. — Arises from radial side of metacarpal 

 of medius in its proximal half, and dorsal surface of metacarpal of 

 annularis in its proximal third. Similar arched tendon, the larger 

 and thicker portion passing to base of first phalanx of medius, 

 whilst thinner portion passes on to palmar surface of metacarpal of 

 annularis. 



Fourth dorsal interosseous. — Arises from dorsal surface of meta- 

 carpal of annularis and radial side of metacarpal of minimus. 

 Inserted into palmar surface of heads of metacarpals. 



Fig. 2. 



S'.f. 



S.l. 



B 



A.E. 



lV\^:^'i--CJI.iP.O 



MD.P. 



Myology of Water-Opossum. 



&., supraspinatus ; /*'., infraspinatus; T.ML, teres minor; Da., deltoid, acro- 

 mial part; l)c., deltoid, clavicular part; B.A., brachialis anticus; S.L., 

 supinator longus ; E.C.R., extensor carpi radialis longior et brevior ; 

 E.G. J)., extensor communis digitorum ; K.M.I)., extensor minimi digiti; 

 S.B., supinator brevis ; £'. 6'. f7., extensor carpi ulnaris ; yi. A,'., anconeus 

 externus ; Tr., triceps; Sb., subscapularis ; P.Ma., pectoralis major; 

 C.B., coraeo-brachialis ; T.Ma., teres major ; C.H., chondro-humeral ; 

 P.Q., pectoralis quartus ; L.B., latissimus dorsi; Tr., triceps; P.L., 

 palmaris longus; P.R.T., pronator radii teres; A.I., anconeus iulernus , 

 E.C.U., extensor carpi ulnaris; F.D.P., flexor digitorum prot'uudus. 



Palmar group. — Five in number and have a common origin in 

 palm. The first three pass to radial side of first phalanges of 

 thumb, index, and medius, whilst the other two pass to the ulnar 

 side of the remaining fingers. 



Intermediate group. — Each finger is provided with a short flexor, 

 each of them consisting of two bellies more or less united and 

 inserted at each side of their respective phalanx, with the exception 

 of the flexor brevis medii, which is single and is inserted into tendon 

 of third dorsal interosseous. 



