40 



INTRODUCTION. 



The pectoral arch falls into two distinct types, — the 

 arciferous (Fig. 16, a), in which the praecoracoid 



Fig. 16. 



Pectoral arch and fore limb of (a) Discoglossus pictus and (b) Bana 



esculenta. Ventral view. 



r. Radius. 



c. Coracoid. 

 ec. Epicoracoid. 



h. Humerus. 

 ost. Omosternum. 

 pc. Prsecoracoid. 



s. Scapula. 

 ss. Supra-scapula. 

 st. Sternum. 

 Ulna. 



u. 



(praecoracoid + clavicle) and coracoid are widely 

 separated from each other distally, and connected by 

 an arched cartilage (the epicoracoid), the right usually 

 overlapping the left; and the firmisternal (Fig. 16, b), 

 in which both prascoracoid and coracoid nearly abut on 

 the middle line, and are only narrowly separated by 

 the fused epicoracoids. The latter type is exemplified 

 by the true frogs (Uanidse) in the adult state, although 



