244 
GEOGRAPHICAL ZOOLOGY. 
[PART IV. 
uniformity of climate, would naturally lead to less development 
of such a group as this, than in the vastly more extensive 
and varied and almost equally luxuriant Palsearctic region of 
Eocene and Miocene times ; while on the other hand the greater 
number of the smaller Carnivora in the tropics during the Plio- 
cene and Post-Pliocene epochs, would he a constant check upon 
the increase of these defenceless animals, and no doubt exter- 
minate a number of them. 
The Eodents thus offer a striking contrast to the Ungulates ; 
and these two great orders afford an admirable illustration of the 
different way in which physical and organic changes may affect 
large and small herbivorous Mammalia; often leading to the 
extinction of the former, while favouring the comparative develop- 
ment of the latter. 
Order XL— E DENT A TA. 
Family 71. — BEAD ZPODIDAE. (3 Genera, 12 Species.) 
General Distribution. 
Neotropical 
Sub-regions. 
Nearctic 
Sub-regions. 
Pal^e arctic 
Sub— regions. 
Ethiopian 
Sub-regions. 
Oriental 
Sue- regions. 
Australian 
Sub-regions. 
The Sloths are a remarkable group of arboreal mammals, 
strictly confined to the great forests of the Neotropical region, 
from Guatemala to Brazil and Eastern Bolivia. None are found 
west of the Andes, nor do they appear to extend into Paraguay, 
or beyond the Tropic of Capricorn on the east coast. The genera 
as defined by Dr. Gray in 1871 are : — Cholcepus (2 sp), “Sloths 
with two toes on fore limbs, sexes alike/ 1 Costa Eica to Brazil ; 
Bradypus (2 sp.), " Sloths with three foes on fore limbs, sexes 
alike,” Central Brazil, Amazon to Bio de Janeiro ; Arctopitheciis 
(8 sp.), <f Sloths with three toes on fore limbs, males with a 
coloured patch on the back,” Costa Eica to Brazil and Eastern 
Bolivia (Plate XIV., vol ii. p. 24). 
