(Cope. Wheeler's Survey, vol. iv., pp. 178 _et ss_.)
"Mammalia, with small cerebral hemispheres which leave the olfactory
lobes and cerebellum exposed. The feet short and plantigrade, with
numerous (in the known genera, five) digits, terminating in flat,
hoof-bearing, ungual phalanges. The seven bones of the carpus
distinct, the unciform articulating with both lunar and cuneiform.
The astragalus flat, without trochlear surface, and attached to the
tibia with very little freedom of movement; its distal extremity
divided into two facets, one for the navicular, and the other more or
less for the cuboid. Molars inserted with enamel, with wide crowns
and transverse crests. A post-glenoid process."
This order falls naturally into two sub-orders:
"I. A third trochanter on the femur, and a fossa for the
round ligament: no alisphenoid canal; superior incisors
present _Pantodonta._
"II. No third trochanter, nor fossa for the round ligament;
an alisphenoid canal; no superior incisors. _Dinocerata._"
This sub-order, Dinocerata, includes at present three distinct
genera, _Uintatherium_, Leidy, _Dinoceras_, Marsh, and
_Loxolophodon_, Cope (also probably _Megacerops_, Leidy). These three
genera, in addition to the characters above given, are marked by the
possession of two or more osseous projections from the upper surface
of the head; and of these the posterior pair, developed from the
parietals, are the largest.