358 SHOULDER-GIRDLE IN MONOTREMES. 



Rii., Ribs i. and ii. Cc. M. costo-coracoideus. S.Sc. M. 

 subscapularis. S. 8])., M. supraspinatus. St. C. M. sterno- 

 coracoideus. E]). hr. iM. epicoraco-Lrachialis. Sp. C. N. 

 supracoi-acoideus. Sp. C. branch to the M. siipracora- 

 coideus (epicoraco-humeral). jS"/?. iS". branch to M. 

 supraspinatus and M. infraspinatus, r. c. ramus cutaneus. 

 Fig. 5. — (Ornithorhynrhns). The clavicular portion of the deltoid (Dlt. 

 C. ) is shown marked off from the anterior part of the P, 

 major [Pf. M.) The tendinous intersection (Ti.) mentioned 

 in the description of the muscle is shown, and the direction 

 of the fibres of the muscle which are inserted in this inter- 

 section. The P. quartus is shown quite distinct from the P. 

 major. The thick fascia {Ah F.) covering the abdominal 

 muscles, and in which the branches of the intercostal and 

 lateral cutaneous nerves of the thoi'ax ramify, is shown 

 I'eflected. The abdominal portion of the panniculus is 

 seen as a single layer {Pi>. A.), while anteriorly it is shown 

 divided into superficial {Pn. S.) and deep poi-tions {Pn. 

 D. i., Pii. D. ii.). The costo-coracoideus muscle {Cc.) is 

 represented arising from the first rib. 



Fig. 6- — (Ornifhorhynrfms). This figure shows the deep layer of the pan 

 niculus (M. dermo flexor brachii) running to its insertion on 

 the humerus. It is seen divided into three strata. A 

 superior {Pn. D. i.) closely connected with the insertion of 

 the P. major, and lying superficial to that muscle ; a middle 

 {Pn. 1). Hi.) stratum connected with the termination of the 

 P. quartus {Pt. ^^>. ) on the P. major; and a deep stratum 

 which joins the P. major forming an inverted /\ ; a tendi- 

 nous intersection marks their junction (x^. The P. quartus 

 is seen not to be cleft as in Echidna. {Viile fig. 3.) 



Fig. 7. — (Ornilhorhynchus.) The P. major (P^ ilif. ) is shown reflected 

 from the clavicular deltoid {Dlt. C), and beneath the site of 

 the P. major is seen the epicoraco-humeral (^/>. i/. ). The 

 two portions of the biceps are seen {Be. i.. Be. ii.), and a 

 small portion of the long coraco-brachialis {Cb. L ) is shown 

 lying beneath {Be. ii.). The coraco-brachialis brevis is a 

 wide muscle, and is seen between (Be. i. and Be. ii.) and 

 between (Be ii. and Cc) The costo-coracoid (Cc.) is shown 

 arising from the first rib. The nerve supplying the P. 

 major (36) with its branch (37) to the P. quartus is seen ; 

 and also the cutaneous branch of the N. supracoracoideus 

 (Sp. C.) is represented. 



Fig. 8. — {Ornithorhynrhu^). The clavicular deltoid is pinned up, and its 

 nerve of supply (28) from the N. axillaris (27) is shown ; 

 also the branch from (27) to the scapular deltoid (29). The 

 N. supracoracoideus is seen giving off a branch (22a) to the 

 epicoraco-humeral {Ep. H.), muscle ; a branch (25 and 26) 

 to supply the supraspinatus (iS'.^'.) and infraspinatus (/. <9.) 

 muscles. A small cutaneous branch (23) is represented in 

 the figure as running towards the median line : it comes to 

 the surface between the clavicular deltoid and the P. major. 

 A large branch (23a and 24) is seen entering the deltoid, to 



