126 The American Naturalist. [February, 
Upon the whole we find that primitive and second- 
ary ungulate characters decidedly predomi- 
nate in the skull, teeth and skeleton. The 
secondary characters, especially in the ankle and wrist joints, 
are parallel with those in the perissodactyls, and are not 
mingled with unguiculate adaptations until we reach the 
phalanges. 
Relation to the Unguiculata. Cope was the first to advocate 
the more radical view that this genus represents a distinct 
order. He wrote: “It has little relation to the family of Per- 
issodactyla to which it has given the name (Paleosyops). 
Unlike the serial manus and pes of the edentata the carpus 
and tarsus are here diplarthrous in structure or displaced upon 
each other. While the Condylarthra are ungulate with an 
unguiculate carpus and tarsus, this order Ancylopoda presents 
the antithesis of including unguiculates with an ungulate car- 
pus and tarsus.” This antithesis he assigned as the main — A 
character of the new order? He still considers the form of 
the terminal phalanges as of fundamental importance and 
believes (in a letter of May 14, 1892) that Chalicotherium must 
have been derived from some primitive unguiculate. 
Lhe ancestry of Chalicotherium. Without any knowledge of 
the ancestors of Chalicotheriwm we thus reach a dead lock. 
Shall the unguiculate structure of the phalanges outweigh the — A 
ungulate structures in other parts of the skeleton? Is it pos- 
sible to derive such a skull and skeleton from any unguiculate 
or such terminal phalanges from any ungulate? In looking 
about for relatives of this genus we must now entirely discard 
the Palæosyops group, and hunt among the lowest Eocene 
types. The lowest Eocene unguiculates are wholly dissimilar. 
The only form at all similar is the genus Meniscotherium. 
Meniscotherium was a little plantigrade slightly larger than 
_. Hyrax, and of very similar proportions. It is found in the — a 
beds between the Wahsatch and Puerco and was even older than _ - 
Coryphodon. The teeth are of the ungulate type known aS 
 7Gil’s term “Chalicotheroidea” was applied to these forms, considered 
as a super-family, equivalent to the Camelide, Giraffidæ, etc., and not as 4 n 
suborder. Arr. Fam. of Mamm., 1872, p. 71-77. 
