~ 
130 ‘The American Naturalist. [rebrand 
a third lobe to the last lower molar. The resemblance between 
the skulls of these two types is also very marked in the whole - 
region behind the infra-orbital foramen. We see the same 
form of cranium, occiput, and auditory region. 
I conclude, therefore, by giving a table of the résemblances 
and differences between the two types. Both are numerous, 
The question is, which are most fundamental ? 
MENISCOTHERIUM. CHALICOTHERIUM. 
1° Cutting teeth somewhat reduced............ Reduced or rudimentary. 
s per molars, buno-selenodont e same ooo 
A short posterior crest. Protocon- The same. Protoconule re- 
ule large. duced. 
Lower molars \opho-selenodont The same. 
Metaconulid reduplicate. No 3rd 
lobe on Mè. ` The same. 
2° Five digits. Functionally tri- Three digits. Structurally — 
dactyl. Mesaxonic. tridactyl. Not mesaxonie, 
Carpus and tarsus, serial, (un- 
guiculate type)........ Displaced (ungulate type). 
3° Centrale, tibiale, 3rd trochan- 
ter, entepicondylar foramen, 
Fibulo-calcaneal facet All wanting. 
4° Terminal phalanges sub-ungu-............... Unguiculate. 
ate. 
5° Plantigrade. Sub-digitigrade. 
Many of these differences are such as separate higher from 
lower forms, especially those under 3° and 5°. We witness 
the loss of the primitive characters under 3° in many distinct 
phyla, also the modification of the characters under 2° and 5°. 
I have now endeavored to clearly state the pros and cons 
of this question. The evidence for the original ungu- 
late affinities of the Ancylopoda seems to me much stronger 
than that for its purely unguiculate origin. Supporting this 
view is the strong likeness of the skull and teeth of Chalice 
therium to those of Meniscotherium, and finally the analogies 
which it presents to the perissodactyls in the modernization of 
the feet, wrist and ankle. My conception of its origin and 
zoological relations can be expressed in the following diagra™- 
aay ogee 
Pan 
Reh as 
eS EE 
