PETERSON: A REVISION OF THE ENTELODONTIDAD 101 
rations of the pedicle and transverse processes continue to be of large size up to the 
thirteenth dorsal. There is only a slight suggestion of the metapophysis on the 
twelfth dorsal vertebra. 
Thirteenth Dorsal Vertebra. — In the region of the thirteenth dorsal there is an 
important change in the dorsal series. ‘The neural spine was still, no doubt, of the 
dorsal type, but short. The anterior zygapophysis is also of 
the dorsal type, while the postzygapophysis fits into a nearly : 
typical lumbar articulation of the succeeding vertebra. The ~ 
transverse process is quite heavy and has an almost flat sur- ; 
face for the tuberculum of the rib. The metapophysial 
area is divided into three small tubercles and the superior 
aspect of the transverse process is on tlie whole very rugose. 
The vertical perforation is very small and is placed near the 
anterior margin of the neural arch. The horizontal canal 
for the transmission of the spinal nerves, which perforates 
the wall of the neural arch between the posterior capitular 
and the tubercular facets is of large size. This vertebra 
appears to correspond most closely with the vertebra described by Professor Scott 
as the eleventh thoracic vertebra in Archexotheriwm ingens (87, p. 293). 
Fourteenth Dorsal Vertebra. —The fourteenth dorsal of Dinohyus agrees most 
¥ia. 53. Lateral View of 
Thirteenth Dorsal of D. hol- 
landi Peterson. } nat. size. 
closely with the one which Professor Scott regards as the twelfth of Archxotherium 
ingens. In Dinohyus this vertebra differs in many important characters from either 
the twelfth or thirteenth dorsals in the Princeton specimen in which the thirteenth 
is the last dorsal according to Scott. From both the twelfth and the thirteenth in the 
latter specimen the fourteenth thoracic vertebra in Dinohyus differs in having a very 
well developed transverse process, a large perforation through the sides of the neural 
arch back of the capitular facet for the last rib, and the absence of anapophyses. 
The superior portion of the neural spine is broken off, but its broad antero-posterior 
aspect indicates that in shape it closely resembled the lumbar vertebre. The pos- 
terior zygapophysis is identical in form with that of the twelfth (thirteenth ?)“ in 
Archeotherium. As Scott has shown in his memoir, page 293, the cross-section of the 
zygapophyses of the lumbar vertebrae present an S-like outline which causes the 
development of large episphenial processes. The neural canal is transversely broad, 
but low. The centrum is well rounded and has no ventral keel or prominent rugosi- 
ties for muscular attachments. ‘The facet for the last rib is of large size, oval in 
‘\'The writer is of the opinion that Archwotherium from the Oligocene may have had fourteen thoracic (dorsal) 
vertebrae thus agreeing in its vertebral formula with Dinohyus. 
