XIII.] 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 glen&idal 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 coracoicL Where the <joracoid unites 

 with the scapula it contributes to the forma- 

 tion of the glenoidal cavity. 



& 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 prae- 

 coracoid lies a bone, the clavicle, the outer end 

 of which articulates with the coracoid and 

 . scapula, the inner with the omosternum. 

 Draw the whole pectoral arch carefully, shading differ- 

 ently the bones and cartilages. 



f. The bones of the fore-liml). 



a. The arms-bone (humerus). 



