vil AMERICAN OPOSSUMS a 
course the chief interest of the genus, which may be “an un- 
modified survivor from Mesozoic times, and therefore from a 
time long before the Didelphyidae, Peramelidae, and Dasyuridae 
were differentiated one from the other.” Another ancient feature 
SSF ase Uae 
Fig. 82.—Banded Australian Anteater. Wyrmecobius fasciatus. 
(found in Jurassic mammals) is a mylo-hyoid groove upon the 
lower jaw, which, however, is not always present, and its exist- 
ence has therefore been denied. The single species, JZ fasciatus, 
is partly arboreal and partly terrestrial in habit, and feeds upon 
ants. It is a Western and Southern Australian form. 
Fam. 2. Didelphyidae.— All the members of this family are 
pentadactylous. The 
teeth are fifty in number, 
arranged thus: 13 C1 
Pm 3 M#¢. The caecum 
is small; the pouch is 
generally absent; the 
tail generally long and 
prehensile. 
The genus Didelphys 
contains most of the 
forms belonging to this 
family, including as it 
does some twenty-three 
species. The Opossums 
are mainly arboreal ani- ; 
mals, insectivorous in Fic. 83.—Virginian Opossum, Didelphys virginiana. 
their food ; but the larger Seaeaves ey 
species eat reptiles, birds, and their eggs. Several of the small 
species carry their young, when able to leave the teats, on 
