36 



E. M. MUSEUM MEMOIRS. 



Caudal Region. 



Length of first four vertebrae (g inches) 



First vertebra, fore-and-aft diameter of centrum 



do., diameter of neural canal 



do., extent of transverse process 



Several of these vertebrae were figured in the first Bulletin of the 

 Museum. 



Comparison with the Proboscidia. Several comparisons with the spinal column 

 of mastodon have been already commented upon. In summary : the cervical 

 vertebra of Uintatherium have longer centra and possess shorter neural spines ; 

 in the dorso-lumbar region, anteriorly the neural spines are shorter and lighter ; 

 the centra have the same proportionate length ; the articular facets for the ribs 

 correspond closely. Posteriorly LoxolopJiodon diverges in the great develop- 

 ment of the metapophyses, and consequent closer articulation of the vertebrae. 

 The pleurophysial elements of the sacrum are much more expanded, and present 

 broader attachments with the sacral surfaces of the ilia. The caudal vertebras 

 are broader, and have more slender spines. 



Compariso7i with RJiinoccros. The vertebrae of Rhinoceros differ widely from 

 those of the Dinocerata. The vertebral artery passed through the superior 

 arch, instead of the transverse process, of the Atlas. Throughout the cervical 

 series the zygapophysial faces are more oblique, the spines longer, the centra 

 more flattened and deeply cupped behind. In the dorso-lumbar region the ver- 

 tebrae are still decidedly opisthocoelous ; the spines are very long in the lumbar 

 and high above the sacral surfaces in the sacral region. The metapophyses differ 

 widely from those of Loxolophodon. They are represented in the lumbar region 

 by short, forward-directed spines ; they do not therefore support the zygapo- 

 physial faces which are found instead upon the laminae. 



Ribs. 



The collection contains ribs from several portions of the chest ; they bear a 

 general resemblance to those of the elephant, although much fighter, thus in keep- 

 ing with the narrower chest. The most anterior has a stout head and well-raised 

 tubercle. The shaft arches strongly outwards to the angle beneath the tubercle, 

 and then turns rapidly downwards. The shape of the first rib indicates a nar- 

 row opening at the neck. The outer face of the rib is much roughened for the 

 attachment of the muscles which swing the scapula. As in Elephas, the head is 

 divided by a median groove. The succeeding ribs are deeply grooved in front 

 and much less so behind. The neck is somewhat longer throughout than in 

 Elephas ; the angle is more acute, the tubercle more prominent. 



.252 

 .061 



•035 

 .085 



