The Artiodactyla. 1089 
of India, but a species has been found in Algerian deposits, and a 
large form, Hippopotamus major, is abundant in the Plistocene of 
Southern Europe. Ofthe Hyotheriine the most generalized form, 
Hyotherium, is represented by several species in Europe and India’ 
In its characters it is the most primitive of the family excepting in 
the weakness of the canine teeth. It is nearer the ancestral genus 
of the family than any that is yet known. In Bothrolabis we have 
a distinct approach to Dicotyles, of which it is probably the ancestor. 
Four species from the John Day or Middle Miocene of Oregon are 
known. They were of the sizes of the existing peccaries. The 
genus Platygonus embraces extinct species of North America 
and Mexico. P. vetus Leidy has left remains in the Pennsylvania 
Bone Caves. It was larger than the white-lipped peccary. P. 
alemani Dugés has been found in Mexico. 
Several extinct species of Dicotyles are known, from the North 
American Plistocene and ? Pliocene. One of them, D. nasutus 
Leidy, has a more elongate muzzle than any of the recent species. 
. The Elotheriinse embrace the oldest known forms of the family, 
dating in geological time from the Lower Miocene or Oligocene, 
and terminating with the summit of the middle Miocene. But one 
genus is certainly referable here, the Elotherium of Pomel; but a 
second, Tetraconodon Falconer, may belong in the same group. 
As the feet of the latter are unknown, the affinities cannot be yet 
determined. It differs in the inferior dentition from Elotheriam 
by the huge size of its premolar teeth. Elotherium is represented 
by species over the Northern Hemisphere. The E. magnum is the 
only one known from Europe. It was larger than the domestic 
hog. The Æ. mortoni Leidy of North America was about the size 
of that animal. Its remains are common in the beds of White 
River age. It was accompanied by a huge species, the E. ramosum 
Cope, which has a skull as large as the Indian Rhinoceros. In 
all the species of this genus the mandibular ramus has two osseous 
projections, one opposite the symphysis, and the other well behind 
it. These are represented by wattles in old males of the recent hog. 
In the E. ramosum these tuberosities become processes, and the an- 
terior ones especially are so long that when the chin was stretched, 
hog-like on the mud, it was raised well above the surface, allowing 
the passage underneath of water or of small animals.. In the John 
