124 
The American Naturalist. 
[February, 
CHARACTERS OF CHALICOTHERIUM. 
Shared by Ungulates. 
Radius transverse 
proximally, with two 
fossæ for humerus. 
Tibia with two fossze, 
_ spine and crest. 
um with 
broad sustentaculum. 
iplarthry in carpus 
and tarsus. 
Shared by Perissodactyla. 
Tridactyl manus and 
pes. 
Astragalus and 
carpal and tarsal facets 
diplarthrous. 
` Not found in Perisso- 
dactyla. 
Not mesaxonie. 
fourth digit. 
Secondary unquicu- 
ate modifications of 
limbs and phalanges. 
Third trochanter ab- 
sent. 
' Large curved tym- 
Buno-selenodont 
Jaws with elevated molar type. 
condyle and broad an- 
panic bull. i 
Reduction of upper 
gle. incisors. 
Molar teeth of sexi- 
tubercular origin. : 
This table shows that there are many characters, beside the 
form of the phalanges, which excludes this family from the 
Perissodactyla proper. The detailed comparisons of the skull 
which Depéret institutes with Palxotherium and Palsosyops 
relate to structures which are shared by all primitive Ungu- 
lates. The only structures if which there is apparently con- 
clusive evidence of a remote relationship to this great division 
of the Ungulates is first in the teeth and second in the carpus 
and tarsus. It remains, therefore, to be seen whether these 
- also are products of homoplasy or “parallel adaptation,” oF 
whether they really evince affinity. 3 
Now let us turn to the broader question. Is Chalicotherium 
to be classed as an ungulate or as an unguiculate in the Lin- 
nean sense? We should, of course, compare it first with the 
primitive ungulata which exhibit many unguiculate characters. 
We are again guided partly by the excellent figures and descrip- 
tions given by Depéret of C. magnum (race Rhodanicum). The 
skull resembles that of the Ungulata Condylarthra in many — 
features. The occiput is very low and broad and widely over- 
hangs the condyles. There is a well arched sagittal crest and 
a rather small cranium. The lower jaw has an elevated con- 
dyle and a deeply extended angle. The external auditory 
meatus is widely open below and there is a large mastoid pro- 
