AESINOITHEEITJM. 



25 



large and massively constructed ; anteriorly it is bounded by the sharp border 

 just mentioned ; posteriorly, on the other hand, it has a broad flat surface, and it 

 is perforated near its base by the vertebrarterial canal {f-tr.). Its outer ends 

 form broad, roughened, rather convex surfaces. 



Text-fig. 8. 



as. 



Atlas vertebra of Arsinoitherium zitteli : A, from back ; B, from front ; C, from abore. 



ax., lateral surface for axis ; cond., surfaces for occipital condyles ; f.tr., vertebrarterial canal ; n.s., neural 

 spine ; od., surface for odontoid process ; sp./., foramen for first spinal nerve ; t.p-, transverse process. 



i nat. size. 



This atlas differs from that of the Dinocerata in being much wider, and in 

 having longer transverse processes and a less convex neural arch. From the 

 atlas of Elephas it differs in its much longer transverse processes, less convex 

 arch, less developed spinous tuberosities, and smaller vertebrarterial canal. In 



E 



