Apf. 1903. North American Plesiosairs — Willis ion. 



4i 



lar cartilage. The ventral or clavicular (proscapular) extremity 

 is broad and thin and deeply concave on its visceral surface. 

 Its inner border is rounded for the most part and thin, except 



Fig. 6. 



Fart of right scapula of Plesiosaurus wudgei Cragin, external (.left and internal (right) views. 



on the anterior part, where it is moderately thickened, as though for 

 cartilage. The posterior and inner border is quite thin throughout 

 and evenly concave, forming the outer anterior border of the scapulo- 

 coracoidal foramen. The anterior border is sinuous and thinned, 

 having a knife-like edge throughout its whole extent. The exterior 

 border, between the glenoid and suprascapular extremities, is deeply 

 concave, with the mar- 

 gin thickened and 

 convex. The ventral 

 surface of the bones 

 tonus two nearly flat 

 planes, meeting in a 

 straight. prominent 

 ridge, which extends 

 from the ventral side 

 of the anterior border 

 of the glenoid surface 

 to the anterior angle 

 of the ventral ramus. 



The two surfaces meet ., . ,',',„ . 



Ventral extremity ol scapula of PUstosaurus gulo Cope (type 



in a very obtuse specimen), one-half natural size. 



angle. The visceral 



surface is, for the most part, concave. On the ventral ramus this 



concavity is marked, receiving the clavicle on its anterior part. 



There is a sutural roughening continued along the anterior border 



