The British Guiana Museum. 217 
the small ant-eater (Cyclothums didadlylus) the snout is 
quite short, the tail prehensile for an arboreal mode of 
life, and the feet two-toed. 
These groups, the -sloths, armadillos, and hairy ant- 
eaters, are confined to the Neo-tropical or South American 
Zoological region. These, together with a few other 
types restricted to certain limited areas in Asia and 
Africa, though but of a low grade of mammalian organis- 
ation, yet present a decided advance on the marsupial 
type already described, and are placental animals, the 
young being nourished before birth by the vascular 
strufture known as the placenta. They are members ot 
the great group of the Edentata — a group name derived 
from the nature of the teeth which are never replaced by 
a second set in these animals, and are destitute of enamel ; 
while incisors or front teeth are never present. This 
group of animals is evidently a remnant. During late 
geological periods it was widely distributed ; and before 
the ar£tic conditions of the last glacial period brought 
about influences tending to their extinction, gigantic 
forms roamed in the forests, more especially in this very 
South American region, where, at the present time, the 
group is most abundant. 
Different species of the yawarries or opossums (Di- 
delphys, sp.J are also shewn. These animals belong to 
the group of marsupials already described, and are 
monkey-like forms with prehensile tails, and with the 
hind feet converted into prehensile organs or hands 
for an arboreal life. The pouch in these forms is 
much reduced, and becomes too small, in many species, 
for the support of the young. The opossums are 
confined to North and South America, not being found 
