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84 BOMBAY NATURAL HISTORY SOCIETY. 
varieties are very common in some cases, the characters by which one 
form is distinguished from another are observed to sink in impor- 
tance the more thoroughly they are investigated, and it would seem 
that there is quite as much reason for separating the Enropean man 
from the Australian savage as there is for placing the zebra and 
horse in distinct species. Sharply as the Hquide as a group are 
defined, it is wonderful how few essential points of difference they 
present among themselves. Some naturalists refuse to accept the 
differences as more than specific, and thus describe each form as 
Kquus. Others consider as horses those which have chestnuts and 
castors, % ¢., “warts,” on both fore and hind legs, and classify the 
asses and zebras together as being devoid of castors. The retention 
of castors, though apparently avery petty matter, seems certainly 
to havea value in systematic classification. Hamilton Smith goes 
further and insists on giving the zebras and their allies a distinct 
generic name, Hippotigris, and, considering their distinct googra- 
phical range and apparently long special descent, the South African 
Kiquidee seem worthy of this distinction, which leads us to the follow- 
ing classification :— 
EQUID Ai. 
asi Diane nce. aes es ts ta 2 = i 
Horses (quus). (Asinus). ZwBRAS (Hippotign 
1. Equus. Aginus. * 1. Zebra. 
2. Burchell’s Zebra. 
3. Quaggs. 
., Onager, 
L 
2 
8. Hemippus. 
4 
6 
OR ed 
Teoniopus. 
Hemionus, 
It must be remembered that the carly naturalists especially have 
confused certain of these forms, or, ab any rate, their names. Thus 
but since then 
hemionus was applicd first by Pallas to the kiang, 
has been used for the onager or for hemippus. A less serious confu- 
sion is the use of the term onager for the Assyrian wildass (As. 
hemippus) instead of for the wild ass of Cutch; but competent 
naturalists, such as Sclater, doubt whether there really is any differ- 
ence between the onager and the hemippe, while others consider 
taoniopus is also simply a variety of onager, Thus the asses would 
tend to become only three forms, the true ass, onager, and the kiang. 
Jiven this reduction is by some considered insufficient, and Asinas 
vulgaris is taken to have direct and immediate relation with the 
onager, either as progenitor or descendant; some observers specially 
notifying Taniopus as the variety most directly related in descent 
to the common domesticated ass, in support of which view we shall 
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