360 O. C. Marsh— Vertebrate Life in America. 
believe the specimens now at New Haven will demonstrate 
the fact to any anatomist. They certainly carried prompt 
conviction to the first of anatomists, who was the honored guest 
of the Association a year ago, whose genius had already indi- 
cated the later genealogy of the horse in Europe, and whose 
own researches so well qualified him to appreciate the evidence 
here laid before him. Did time permit, 1 might give you at 
least a probable explanation of this marvellous change, but 
justice to the comrades of the horse in his long struggle for 
existence demands that some notice of their efforts should be 
placed on recor 
Beside the Horse and his congeners, the only existing Peris- 
sodactyles are the Rhinoceros and the Tapir. The last is the 
oldest type, but the Rhinoceros had near allies throughout the 
Tertiary ; and, in view of the continuity of the equine line, it a 
well worth while to attempt to trace his pedigree. At t 
bottom of the Eocene, in our Western lake-basins, the peor 
genus /elaletes is found, represented by numerous small mam- 
mals hardly larger than wer diminutive horses of that day. In 
Miocene west of the Rocky Mountains, this line seems to pass 
on through the genus Diceratherium, and in the higher Miocene 
this genus is well represented. Some of the species nearly 
equaled in size the existing Rhinoceros, which Diceratherium 
strongly resembled. The main difference between them is a 
most interesting one. The rudimentary horn-cores on the 
nasals, seen in Colonoceras, are in Diceratherium developed into 
as in the Ruminants, and not on the median line, as in all 
existing forms of Rhinoceros. In the Pliocene of the Pacific 
Coast, a large Rhinoceros has been discovered, which may 
e a descendant of Diceratherium, but as the nasal bones have 
not been found, we must wait for further evidence on = 
The upper Eocene Stan Amynodon is the oldest known 
Rhinoceros, and by far the most generalized of the family. 
