Apr. 1903. North American 1'i.esiosaurs — Williston. 



23 



sphenoid in this specimen. There is, however, a slight projection in 



the middle of the opening behind, which may represent a more 

 extensive ossification, but it seems very probable that there was a 

 real vacuity here, unlike the condition in Pc/onct/stcs and Plesiasaurus. 

 The union with the vomer is oblique, from without inward and 

 forward. 



The pcUatine and ectopterygoid on one side, though retaining 



Fig. 1. Fig. 2. 



Palate of PeUneustes. Palate of PUsiosavrus. 



/'.v.. premaxilla; w.v., maxilla; v., vomer; m., internal nares; /<7., palatine; />/., pterygoid; 

 /i'., posterior palatine vacuity; cp., ectopterygoid; f>s.. basisphenoid; fio., basioccipital; (/..quad- 

 rate; .c</.. squamosal. After Andrews. 



their original positions approximately, were free in the specimen ; 

 they are complete and show their sutural relations very well. On the 

 Other side, they are both in position. The palatine is a long, narrow, 

 thin bone, concave from side to side above, and correspondingly con- 

 vex below. The inner, slightly sinuous margin is thin, and overlaps 

 the outer margin of the palatine process of the pterygoid. Near its 

 anterior extremity there is a small emargination for the nares*, where 



'See description of the palate in Brachaucheniut beyond. 



