Apr. 1903. North America** Plrsiosaurs — Williston. 



45 



been covered with cartilage below, leaving a free, convex, ventral 

 surface, elongate oval in shape, including the emarginations, limited 

 by a distinct ridge or angle. The striation of this thinned margin 

 points to a covering of cartilage. The anterior emargination of the 

 bone is narrow and deep, while the posterior one is broader and « \ > n 

 deeper. It differs markedly from the corresponding bone of PL mudgei 

 (see PI. XXVII), in its less broad and deep emarginations. An 

 episternum which I provisionally refer to the species Tr. anony- 

 mini, herewith figured, resembles that of D. osborni more closely. In 

 all three, perhaps belonging to distinct genera, it will be seen that 



Fig. 10. 

 1, Episternum and clavicles of Muratnotatana ; 2. 3. the same of PUsiosaurus, from above and 

 below. After Seelev. 



