46 



Sauropterygia. 



Wall-case, 

 No. 13. 



Table-cases, 

 Nos. 6,7, 8. 



Fig. 61.— Anterior and left lateral aspects of a cervical vertebra of CryptocUdiis (?) 

 Richardsoni (Lydekker) from the Oxford Clay, Weymouth, Dorset. ^ nat. size, 

 CO, rib ; j)rz, prezygapophysis ; ptz, postzygapophysis. 



caudal vertebrae carry true ribs and also chevron bones. In 

 the pectoral girdle, the coracoids unite in a ventral symphysis, 

 and the scapulae may also meet in the median line. The limbs 



Fig. 62. — Ventral aspect of the pectoral girdle of Plesiosaurus Hawkinsi (Owen), from 

 the Lower Lias, Street,Somerset (about J nat. size) oit.,claviculararch; sc, scapula; 

 poor., ventral (precoracoidal) plate of scapula ; (jl., glenoid cavity ; cor., coracoid. 

 (In reality the clavicular arch is wedged in between the extremities of the coracoids.) 



vary, being in some genera adapted for progression on land, in 

 others converted into paddles suited for an aquatic existence. 

 The humerus and femur are always of considerable length; the 

 phalangeal bones aie elongated, but no additional digits are 

 developed. In habits the members of this order were carnivo- 

 rous, and either marine or terrestidal. 



