144 Prof. H. G. Seeley. The Shoulder Girdle 



median crest. It is therefore probable that the clavicles were either 

 loosely articulated to its margin, or extended between the interclavicle 

 and scapula. 



FlG. 11. — Yentral aspect of interclavicle, Murcenosaurus beloclis ; Clav. may be a 

 portion of the thin left clavicle upon its ventral surface. 



There is no other example of an interclavicle received between the 

 scapnlo-precoracoids as in this species, for the anterior notch between 

 these bones in advance of their sutural surfaces is not unlike the 

 notch already described under the heading (i), except that it is less 

 well denned and more irregular and narrower, and it is into this 

 notch that the base of the interclavicle is articulated. In its posterior 

 part the surrounding bone is thick, forming a concave channel on 

 each side, which is limited in front on the visceral surface by a 

 tubercle, anterior to which is a small transverse notch on each side in 

 the scapular bone, which becomes thin as it extends forward, thus 

 making the clavicular cavity + -shaped. There is every appearance 

 of cartilage having extended between the opposite scapular margins, 

 so that the interclavicle may have been hidden upon the ventral 

 surface, and the anterior part of that bone may not have been in 

 actual contact with the thin scapular plate in front of it. The 

 position of the interclavicle appears to show that it ossified prior to 

 the bones between which it is placed. 



In this series of Elasmosaurians there is seen a remarkable change in 

 the condition of the clavicular arch. In the first species described 

 it is large and much broader than long, and placed behind the 



