, 
CLASSIFICATION. 19 
this arrangement, for we find that those which have hollow per- 
sistent horns, and those which have solid deciduous horns, or 
antlers, as well as the musks, which have no horns —all have 
feet alike, with four hoofs or toes to each foot, two in front, 
which are active and useful, and two small posterior hoofs quite 
above the others, which seem to be comparatively useless. Then 
we find the camel and the llama have feet quite different from 
the others; while the American antelope, which alone has the 
hollow deciduous horn, and the giraffe, which alone has the solid 
persistent horn, have but two toes to each foot, being entirely 
deprived of the small posterior hoofs, yet having the cloven an- 
terior hoofs, like the ox and the stag. 
We may go further into the anatomical structures of the 
different Ruminantia, and find it convenient to change and inter- 
change these classifications, till at last we despair of arranging 
them into groups, divisions, and classes entirely satisfactory. 
When we descend from these general classifications, and pro- 
ceed to the formation of genera, species, and varieties, the natu- 
ralist meets with difficulties in the expression of general laws 
whose application will lead him at all times to satisfactory re- 
sults. Hence it is that we often find%students of nature disagree- 
ing as to the generic or specific disposition to be made of certain 
individuals ; sometimes because of the development of previously 
unobserved characteristics, and sometimes because of the greater 
or less importance attached to certain or peculiar indicia. 
To meet these many disagreements, and to make certain that 
which would be otherwise uncertain, the student of zodlogy is 
driven to the use of synonyms which in some cases are almost as 
numerous as the authors who have treated originally of the dif- 
ferent subjects. 
It is manifest, then, that I cannot hope to agree either in my 
generic or specific assignments, with all who have gone before 
me, for they do not agree among themselves’; but, beyond this, 
the discovery of new facts will sometimes compel me to make 
new assignments, or to disregard old ones, in obedience to well 
recognized and established laws. 
I shall first treat of the Prong Buck or American Antelope, 
which, in the arrangement suggested, fills, so far as is now 
known, the Second Class of the First Division, of the First 
Group of the Eighth Order, or Ruminantia. This animal pos- 
sesses extraordinary characteristics, some of which were not sup- 
posed to exist in the animal economy, previous to its discovery, 
