244 GEOGEAPHICAL ZOOLOGY. [i-art iy. 



uniformity of climate, would naturally lead to less development 

 of such a group as this, tlian in the vastly more extensive 

 and varied and almost equally luxuriant I'alaiarctic 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 be a constant check upon 

 the increase of these defenceless animals, and no doubt exter- 

 minate a number of them. 



The Piodents 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~EDENTA TA. 

 Family 71.— BRADY POD WJE. (3 Genera, 12 Species.) 



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 Capricoi-n on the east coast. The genera 

 as defined by Dr. Gray in 1871 are : — Chohepus (2 sp.), "Sloths 

 with two toes on fore limbs, sexes alike," Costa Pica to Brazil ; 

 Brachjpus (2 sp.), " Sloths with three toes on fore limbs, sexes 

 alike," Central Brazil, Amazon to Kio de Janeiro ; Ardopitliccus 

 (8 sp.), " Sloths with three toes on fore limbs, males M'itli a 

 coloured patch on the back," Costa Pica to Brazil and Eastern 

 Bolivia (Plate XIA\, vol. ii. p. 24). 



