PLESIOSATJEID^:. 



251 



external surface is markedly rugose. In the more anterior 

 specimens the chevron-facets are confined to the posterior 

 border, but in the hinder vertebrae they occur on both 

 borders. Purchased, 1873. 



Eretmosaurus (?) sp. 



The following vertebrae are provisionally referred to this genus, 

 and indicate a larger form than the type. 

 Hab. Europe (England). 



R. 1360. A series of twelve associated cervical vertebrae, in a some- 

 what crushed condition ; from the Lower Lias of Char- 

 mouth, Dorsetshire. These specimens are placed in at 

 the anterior extremity of the cervical region of the 

 skeleton of Plesiosaurus conybeari, Xo. 40140 (p. 270), 

 under which heading they are again noticed. 



Purchased. 



Genus PLESIOSAURUS, Conybeare \ 



Skull small or moderately large, with short or somewhat elongated 



rostrum and mandibular symphysis. Teeth generally slender, not 



carinated, and the anterior ones usually not enlarged to any marked 



extent. Neck more or less elongated, with the anterior vertebrae 



Li; 



/ / 



Plesiosaurus hawlcinsii. — Ventral aspect of the pectoral girdle ; from the Lower 

 Lias of Dorsetshire. About \. oat, omosternum ; so, pcapula; p.cor, 

 ventral (precoracoidal) plate of do. ; y/, glenoid cavity ; tor, OOraOOld. 



In reality the extremity of tin- omosternum is wedged in between the 

 extremities oft he eoracoids. 



1 Trans. Geol. Sue. scr. 1, vol. v. pt. 2, p. 50U (.1621;. 



