THE EXTREMITIES OF ORVCTKROPUS CAPEXSIS. 



73 



chir'tns (with a few fibres of which muscle it seems to communicate) and the insertion of 



tli 



Prof. Rolleston has pointed out to me a similar high origin of this muscle in th« 



Crocodile. 



Meckel mentions a high origin of the external obliqx ■ from the first rib, as • 

 the Hedgehog and Itaceoon 1 . 



In Dasyjms sexe'ntctus this muscle does not appear to arise from a point hi 



the third rib, immediately posterior to 



til u'e, and in advance of the insertion of 



the seal en 



In one of Curler's plates, however, this external oblique is fi ured 



as 



though taking origin from the first rib, immediately below the lowst fibres of origin .if 

 the si(hclctrius*. 



Deltoid. — This muscle, as in Vasypus, consists of three distinct portions, more or less 

 triangular in shape, which are fairly, but not extend?* ly, developed in proportion to the 

 rest of the muscles of the shoulder. They :ire as follow : 



a. Clavicular. — A flat, triangular, or fan-shaped slip, arising from ihe scapular half oi 



the clavicle, from its inferior or anterior edge, its innermost fibres of origin being at the 



point of attachment of the outermost fibres of insertion of the cleid o- m as f oid 



It 



icn 



passes downwards, along the anterior aspect of the arm, covering at their insertion the 

 factor of the deltoid next to be described, and the pectoralis major muscle, and becomes 

 tendinous at the level of the lowest point of insertion of the latter. Its tendon, with the 

 exception of a slight aponeurotic communicat ion with the somewhat flattened and at- 

 tenuated inferior portion of the tendon of the great pectoral, passes straight on, to join 

 and become fused with that of the biceps, and, eventually, to share its insertion. 



Acromial 



In almost entirely fleshy slip, having half the length of the first 



described factor of the deltoid. It arises from the whole inferior edge of the acromial 

 portion of the scapula — namely, the part included between the strong downward-looking 



metacromial process' and the free extremity of the 



It is in scried into the 



strongly developed "deltoid ridge" of the humerus, immediately external or posterior t< 

 the upper half of the terminal portion of the manubrial factor of the pectoralis major. 

 y. Scapular. —This arises, in part, from the flat oval facet developed upon the spine 



of the scapula at about the middle of its 



part from a tendon which tak 



origin from the anterior half of the scapular spine, and which is also shared by the 

 anterior fibres of insertion of the trapezius. Thence it passes obliquely downwards and 

 forwards, and, on reaching the posterior edge of the " acromial " division of the deltoid, 

 runs into a somewhat broad and thinly flattened tendon, which lies behind the internal 

 face of the above division, and, fusing with it, shares its insertion. 



Cuvier most distinctly figures this muscle as made up of three factors, and, moreoi 



gives the name 



delto'ide a l'avant-br 



»» 



to that factor which I have termed M ela 



VJ- 



but Prof. Humphry 4 notices only two divisions in the specimen which he has 



described 



Supraspinatus. — Arises from the supraspinous fossa of the scapula, and has a very broad 



Vergleich. Anat. loc. cit. p. 454. 

 Op. cit. pi. 254. fig. 2. 



8 Op. tit. pi. 260. 

 4 Loc. cit. p. H99. 



