157 
difference of level between the base of the cranium and the palate ; 
and to the inner side of the posterior molars there is just sufficient of 
the matrix removed to show a slightly raised curved line whose place 
is about that which the edge of the posterior nasal opening should 
occupy, if the animal be organized upon the true Perissodactyle 
type. A further confirmation is afforded by the distinct appear- 
ance of a groove, whose broken edges testify the loss of the little 
piece with which the alisphenoid canal should be enclosed; so in 
the only fragment we possess every character that remains agrees, . 
to help us through the difficulty in which the ambiguous dentition 
leaves us. 
May I be permitted to express the hope, that before forming a de- 
cided judgement on these matters, naturalists will carefully investigate 
for themselves ; recollecting, that so long as man is not infallible, the 
continued progress of research must with new discoveries find some- 
thing to be corrected in that which has been done before? but what- 
ever be the judgement on these points of difference, I trust that doubts 
will cease as to the truth of the original idea, which nought but error 
hindered from being sooner developed ; and that one important step 
may thus be gained towards that correct appreciation of the compa- 
rative value of groups, which we must attain throughout organic na- 
ture, before further generalizations can safely be attempted. 
I will conclude by giving a list of genera arranged as I should now 
propose ; the characters of the groups, although many remain to be 
discovered, are already too numerous to be again repeated, and I only 
include such genera of which I have been able to examine skulls; or 
in the case of fossils, of which actual specimens, casts, or well-authen- 
ticated figures of some characteristic portion of the skeleton have come 
withia my observation. 
ARTIODACTYLA. 
RuMINANTIA. NON-RUMINANTIA. 
Merycopotamus. Hippopotamide. 
Chalicotherium *. Hippopotamina. 
Bovide. Hippopotamus. 
Sivatherium. Hyopotamus. 
Anthracotherium. 
Bos. Chceropotamus. 
Ovis. Adapis. 
Capra. Dicotylina. 
Antilope, and several of Dicotyles. 
the genera into which 
these have been dis- 
membered. 
* Of these two genera I have not yet sufficient evidence to determine the 
family. 
