Xm.] THE FROG. 213 



a. A thin expanded dorsal portion, partly carti- 

 laginous, partly ossified : the supra-scapula. 



/3. Next a bony segment — the scapula, the pos- 

 terior inferior edge of "which is excavated by 

 the glenoidal fossa. 

 The ventral parts of the shoulder-girdle, which 

 lie between the two scapulae, meet in the middle 

 line ; the part on each side is subdivided into 

 an anterior and a posterior portion by a large 

 foramen. 



7. 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. 



S. 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 prcecoracoid-^which, externally, 

 is continuous with the cartilage which lies be- 

 tween the scapula and coracoid and helps to 

 bound the glenoidal cavity. 



^. Closely attached to the fore-part of the prse- 

 coracoid lies a bone, the clavicle, the outer end 

 of which articulates with the coracoid and 

 scapula, the inner with the omostemum. 

 Draw the whole pectoral arch carefully, shading differ- 

 ently the bones and cartilages. 



f. The bones of the fore-limb. 



a. The arm-bone (humerus). 



