THE LIMBS OF AMPHIBIA. 



181 



cartilaginous epicoracoid {e.cr.), wLich hounds it internally ; 

 and a precoracoid, whicli limits it in front. Closely applied 

 to the precoracoid is an ossification in membrane, wMcli 

 represents tlie clavicle. 



The pelvic arch is attached (except in Proteus) to the 

 extremity of the sacral rib. An iliac ossification is always 

 developed ; an ischial, in all but Proteus. The pubis does not 



Tiff. r>7. 



s.sc. 



s.it 



Fijj. 57. -The sternum and pectoral arches of a Frog, seen from above. 

 The left supra-s(^apula is removed :-s<-. scapula; s.sc. supra-scapula ; 

 p.sc. prescapular process ; cr. coracoid; e<-n epicoracoid ; cr./. cora- 

 coid fontanelle. The bar which hounds this m front is the precora- 

 coid, and bears the clavicle : o.st. omosternum ; st. sternum : x.st. 

 xiphisternum. 



appear to be regularly represented by a distinct ossification. 

 In the Batrachia the applied flat Caces of^ the expanded 

 ventral divisions of the pelvic arch coalesce into a disc. 



In the genus Amphiuma, the limbs have each either two 

 or three digits. In Siren, the anterior limbs, which alono 

 exist, are thi-ee or four-toed. In Proteus, the anterior 



