222 ELEMENTARY BIOLOGY. [CHAP. 



into an anterior and a posterior portion by a 

 large foramen. 



y. The bony piece running behind the foramen, 

 from the scapula almost to the middle line, 

 is the coracoid. Where the coracoid unites 

 with the scapula it contributes to the forma- 

 tion of the glenoidal cavity. 



8. The adjacent margins of the two coracoids 

 are fringed with cartilage (epicoracoid), which 

 passes in front of the foramen into a bar of 

 cartilage the pr&coracoid which, externally, 

 is continuous with the cartilage which lies 

 tween the scapula and coracoid and helps to 

 bound the glenoidal cavity. 



e. Closely attached to the fore-part of the prae- 

 coracoid lies a bone, the clavicle, the outer 

 end of which articulates with the cdracoid 

 and scapula, the inner with the omosternum. 



Draw the whole pectoral arch carefully, shading 

 differently the bones and cartilages. 



f. The bones of the fore-limb. 



a. The arm-lone (humerus). 



a. A somewhat cylindrical bone, with an arti- 

 cular expansion at each end and a shaft unit- 

 ing them. 



{3. The great ridge (deltoid crest) on its antero- 

 internal surface, to which a muscle was at- 

 tached. 



The development of this crest is greater in 

 the males than in the females. 



