134 



PROF. OWEN ON GENERIC CHARACTERS 



being strongly convex; while the opposite portion is but slightly- 

 convex and is unridged. A single tooth, like some other fossilizable 

 parts, serves unequivocally to indicate its belonging to a Pliosaur*. 

 I will not dwell on the distinctive characters manifested by the 

 fin-skeleton f, but proceed to detail those shown by the sterno- 



Fig. 1. — Diagram of Sterno-coraco-scapular mass in Plesiosaurus. 



coraco-scapular frame, premising a more detailed description of the 

 characters of that part of the skeleton of Plesiosaurus than has else- 

 where, so far as I can find, been given. 



In Sauropterygia the place and function of a sternum are mainly 

 supplied by the pair of coracoids (figs. 1 & 2, 52) which meet and 



* Id. ib. issued 1861, pi. vii., and 1862, pi. xii. 

 t Id. ib. issued 1862, pp. 9-11, pi. ir. 



