108 



COMPARATIVE ANATOMY 



deles and certain Anura e.g., Bombinator, Fig. 43, C), or else 

 their free edges come into apposition and fuse together (other 

 Anura, e.g., Rana, see Fig. 43, D). In Anurans the procoracoids 

 have a more transverse position than in Urodeles, and come into 



FIG. 85B. PECTORAL ARCH OF THE RIGHT SIDE OF Safamandra maattosa, 

 considerably magnified, and flattened out. 



SS, supra-seapula ; S, scapula (ossified) ; Co, coracoid ; C/, procoracoid ; a, b^ 

 bony processes extending into the procoracoid and coracoid respectively ; 6',. 

 glenoid cavity, surrounded by a rim of cartilage (L). 



connection with the coracoid in the mid-ventral line, thus giving 

 rise to a fenestra between the two. The whole arch is, moreover. 

 more strongly ossified, the procoracoid being covered by an invest- 

 ing bone the clavicle. 



Reptilia. In Reptiles the ossification is still more 'marked. 



The simplest condition of the shoulder-girdle is seen in Chelonians 



(Fig. 86), in which its similarity to 

 that of Amphibians as well as to that 

 of Hatteria is at once seen : no clavicle 

 is developed. 



In other Reptiles the same general 

 plan is retained with modifications. 

 Thus in Lizards (Fig. 44) the well- 

 developed clavicle is more indepen- 

 dent of the rest of the arch and 

 becomes ossified directly, forming a 



S, scapula ; Co, coracoid; Co\ epi- delicate secondary bony lamella ex- 



tending from the scapula to the apex. 



r t i, pnistprml fmnarntiiQ "Rnt it 

 ot tn \ episternal appaiatUS. 



must be remembered that the un- 

 differentiated cells of which it at 

 first consists are in direct continuity with those which form 

 the scapula, Unossified spaces are left in the coracoid, giving 



Co 



FIG. 86. PECTORAL ARCH OF A 

 CHELONIAN. (Ventral view. ) 



coracoid ; Cl, procoracoid ; , 



fibrous band between these two 

 elements ; Fe, fenestra between 

 them ; G, glenoid cavity. 



