PECTORAL GIRDLE REPTILES 



253 



as high in the scale as the turtles. The homology of episternum and entoplastron 

 is more probable, since episterna appear in reptiles, none being known in 

 Amphibia or lower, unless the Anuran omosternum be such, as has been suggested, 

 a view which has its difficulty in that the omosternum has a cartilage origin. 



Theromorpha (fig. 268). — Unfortunately nothing is known of the cartilage 

 girdle, aside from suggestions of its former presence on the edges of certain 

 bones. It is also unfortunate that our knowledge is so deficient with regard to 

 so many of the adults. In general it may be said that- clavicle and episternum 

 are well developed, the former of the two sides often meeting in the middle fine. 



Fig. 268. — Pectoral girdles of Theromorphs. A, Parieasaurtis (Seeley, '93-4); 

 B, Dimetrodon (Case); C, Udenodon (Broom, '02); D, Lahidosaiirus (Williston, '08). 

 c, coracoid; d, clavicle; cm, cl, cleithrum; e, episternum; /5, supracoracoid foramen; h, 

 humerus; pc, precoracoid; sc, scapula. 



All parts are united by suture or by fusion and no motion seems possible between 

 them. Scapula, coracoid and precoracoid surround no fenestrae, and in some 

 there is evidence of an epicoracoid on the margins of the latter bones. The 

 coracoids meet the anterior border of the sternum and the supracoracoid foramen 

 perforates the precoracoid; the scapula was very long in Pareiasaurus. Coty- 

 losaurs had a separate ossification in the position of the cleithrum of fishes. 



IcHTHYOPTERYGiA have a strong lizard-like girdle. The scapula lacks a 

 marked suprascapula, it and the coracoid forming the glenoid fossa. The large 

 coracoids meet in a long symphysis in the middle line; each has a distinct emar- 

 gination in its anterior border, and indications of a former cartilage (like a 



