696 • ME. T. MANNERS-SMITH ON THE [Dec. 4, 



from the transverse process of the atlas in conjunction with the 

 trachelo-acromial. Below, it is inserted into the superior border 

 of the scapula, blending with serratus magnus. It is supplied by 

 a branch of the same nerve which supplies the next muscle. This 

 muscle is called atlanto-scapularis by Coues \ 



Trachelo-acromial. — Is a fairly large muscle. It arises by a 

 narrow strong tendon from the transverse process of the atlas. 

 Below, it is inserted into the spine and acromion process, and also 

 into a small portion of outer end of clavicle. It is supplied by a 

 branch from cervical plexus. Mivart mentions two muscles in 

 this position in Echidna as levator claviculae 2 . This muscle is 

 called atlanto-acromialis by Coues 3 . 



Serratus magnus. — This is a large compound muscle. It arises 

 in separate slips from the lower five or six cervical vertebrae 4 and 

 from the upper three ribs. It is this costal portion only which 

 Coues describes as serratus magnus, costo-scapularis, or s. anticus. 

 The vertebral portion of the muscle consists of two parts, an 

 anterior and a posterior. The anterior passes to the acromion, 

 the posterior to the base of scapula. It is this portion which is 

 continuous posteriorly with the costal part of the muscle ; this 

 latter passing also to the base of the scapula. The whole of these 

 muscles, viz., trachelo-acromial, trachelo-scapula, together with cer- 

 vical and costal part of serratus magnus, appear to be segmentations 

 of one large muscular sheet. The whole sheet might be called 

 costo-scapular. 



Supra-sphiatus. — Is a narrow slender muscle arising from a 

 small portion of costal surface of scapula. It is inserted into top 

 of radial tuberosity. In Echidna it is much larger and fills the 

 whole costal surface of the bone. 



Infraspinatus. — Arises from the scapula immediately below 

 the spine and from the vertebral border. It is inserted just 

 below the head of humerus into the radial tuberosity, beneath 

 epicoraco-brachialis. It is supplied from the upper trunk of the 

 brachial plexus. Testut 5 (quoting Sabatier) says that the infra- 

 spinatus and teres minor are fused in Ornithorhynclms. Coues 

 also considers them probably fused. 



Teres major 6 . — Arises from posterior part of vertebral border 

 of scapula. It is inserted into the humerus just below the head. 



Teres minor. — Is placed underneath infra- spinatus. It arises 

 from the scapula just below the spine, and is inserted close to the 

 head of humerus, more anteriorly than the infra-spinatus. It is 

 supplied by a special branch from the upper part of the brachial 

 plexus. Testut says the muscle is fused with infra-spinatus. 



1 Vide supra. 



2 Proceedings of Linnean Society, 1866. 



3 Vide supra. 



4 This vertebral portion is described by Coues as levator anguli scapulae. 



5 ' Les Anomalies Musculaires,' Testut, 1884. 



This is the part corresponding to the muscle described by Coues as lower 

 part of teres major. The part described by Coues as upper part of teres 

 major would appear more probably to belong to subscapularis. 



