PAL^.OSYOPS LEIDY, AND ITS ALLIES. 
297 
The intervertelu'al notches are mucli smaller than in Rhinoceros, the same being 
the case in all of the dorsals. The centrum of this vertebra has a ^^rominent keel, 
the lateral surfaces on each side of the same being deeply excavated. The spine 
of the fonrth dorsal is very oblique and elongated ; its anterior edge is flat and 
grooved. 
The width of the transverse process has diminished very much and it has 
become raised. These changes are likewise observed in the vertebrm of the Rhi- 
noceros. In contrast with the latter fonn the tubercular facet far exceeds in size 
the capitular. It is deeply concave and looks downward and forward instead 
of outward as in Rhinoceros. 
In the fifth dorsal the transverse processes are exceedingly short and have 
become very much raised. The tubercular facet has become flattened and looks 
more outward and downward. In this vertebra the two facets for the rib nearly 
approach each other in size ; the body and pedicles have become higher as is 
nsnally the case. The post-zygapophyses are more elongated and horizontal than 
in the Rhinoceros. 
In Rhinoceros bicoi'nis in the 6-8 dorsal vertebrm the differentiation of the meta- 
pophysis from the diapophysis begins to appear. In Palceosyops paludos^ls this 
change is not well shown in the sixth dorsal, this being -the last vertebra of this 
series preserved. The transverse process of the sixth dorsal is veiy short and heavy 
distally ; its lamina is strongly triangulai’ and raised. The anterior capitular 
and tubercular flrcets of this vertebra have nearly coalesced. 
Posterior dorsal and anterior lumbar regions. — There are two vertebras in the 
collection which belong to the jwsterior axial region. Their size agrees very closely 
Avith those already described as belonging to P. paludosus, and for that reason I shall 
refer them to this sjAecies. The characters of these vertebrm are highly interesting, 
as they depart Avidely in some respects from those of the recent Tapir and Rhi- 
noceros, approaching more nearly those of Equus. 
The most important difference is found in the pre- and postzygapophyses, and in 
the region of the lamina of the neural arch. The accessory processes are also more 
largely developed than in Tapirus. 
Posterior dorsal . — This vertebi'a, No. 10,286, probably belongs to nearly one of 
the last of the dorsal series, as the position of its articular processes indicates. The 
peculiarities of this vertebra as compared Avith that of Tapirus and Rhinoceros pertain 
especially to the postzygapophyses, Avhich in this species are much elongated and 
placed nearly vertical. In Tapirus and Rhinoceros the processes of the posterior 
dorsal region are obliquely placed and look doAvuAvard and backAvard ; it is only in 
the lumbar region that the postzygapophyses show a tendency to approach the ver- 
tical, but they never reach the position found in Palceosyops. In Eqtms, on the 
other hand, the posterior dorsal region has the posterior articular processes nearly 
vertical, but these processes in the ' lumbar region are not placed as vertically as in 
the dorsal region. Cuvier figures in a lumbar vertebra of Palceotherium magnum 
the same peculiarities in its postzygapophyses as in those of P. pahidosus. The 
