330 SHOULDER-GIRDLE IN MONOTREMES, 



costal portions of the muscle run outwards and forwards they 

 become rapidly narrower. From the ventral border of the costal 

 portion there is now given off a fasciculus of muscle, which 

 running outwards and downwards winds round the ulnar border 

 of the forearm to reach its dorsal surface, where it becomes inti- 

 mately connected with the fascia of the M. flexor carpi ulnaris. 

 This fasciculus repi'esents the M. dorso-epitrochlearis. (Figs. 9, 

 10, D. Ep.) Thfe remaining portion of the costal division develops 

 a tendon, and running inwards and ventral to the tendon of the 

 veitebral ])ortion, becomes inserted on the antero-internal surface 

 of the humerus just internal to the median third of the pectoro- 

 deltoid ridge, and distal to the insertion of the coraco-brachialis 

 brevis. The vertebral portion, which does not become so narrow, 

 runs to be inserted by a well-marked flat tendon on a strongly 

 developed ridge situated on the distal narrow portion of the 

 antero-internal face of the humerus, reaching almost to the coraco- 

 brachialis longns insertion on the ento-condylar I'idge. (Fig. 9, 

 Lt. D.P.; Lt. D.A.) 



Relations. The digitations arising from the posterior ribs 

 are intimately connected with the dermo-dorsi cervicalis, and the 

 trapezius. The fibres of the sacro-lurabalis running over the ribs 

 have the same direction as the fibres of the latissimus dorsi : no 

 doubt this induced Owen to describe the latissimus as arising from 

 the posterior ribs, lumbar region, and pelvis. At its insertions on 

 the humerus the tendons are hidden from view by the biceps and 

 coraco-brachialis longus. 



Innervation. Echidna : Latissimus dorsi (a) scapular 

 portion, from vi. cervical nerve ; (b) anterior dorsal portion from 

 vi. and vii. cervical nerves. (Fig. 13; 38-40.) Ornithorhynchus: 

 anterior and posterior dorsal portions from vi. and vii. cervical 

 nerves. (Fig. 16; 39-40.) Echidna: Dorso-epitrochlear, vii. 

 cervical nerve. Ornithorhynchus : vii., viii., cervical nerves, and 

 i. and ii. dorsal nerves. 



Westling — Echidna : Scapular and anterior dorsal portions : 

 "Die beiden Portionen des Muskels werden von zwei aus den 

 JVI. cervicales v., vi. and vii. ausgehenden Nn. subscapulares 



