SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. ^2 



Tylosaunts was a long, slender-bodied reptile some 25 feet in 

 length, having the limbs modified into short swimming paddles, with 

 a long, powerful, compressed tail. It was predatory in habits, living 

 on fishes and probably also on the smaller individuals of its own kind. 

 One of the unique features of the skeletal structure is the presence 

 near the middle of the lower jaw of a joint which permits it to bow 

 outward. This featvire in connection with the loose articulation at 

 the extremities allowed the jaws to expand and thus enabled the 



Fig. 21. — The swimming reptile 'rylosaurus dyspclor in process of 

 preparation for exhibition. Photograph by Bassler. 



animal to swallow large objects. In life the l)ody was covered by 

 small horny scales. A study of this specimen is being made by 

 ]Mr. C. W. Gilmore, and the results of his investigations will be pub- 

 lished in the Proceedings of the U. S. National Museum. 



In figure 22 is shown another of the recently mounted skeletons — 

 that of the large extinct Rhinoceros-like mammal from the Tertiary 

 (Oligocene) deposits of western Nebraska, named by Osborn Bron- 

 totheriitm hatchcri. The bones of this skeleton were foimd em- 



