DIBELPHID.K. 
404 
agree more closely in their form and arrangement with those 
of the Dasyuri. The molar teeth of the Opossums differ 
from those of the Perameles group in wanting the posterior 
inner lobe, and in this and every other respect they agree 
with the molar teeth of the Dasyuri. The structure of the 
skull, and of the extremities, is nearly the same in the last- 
mentioned group and the Opossums ; the only difference 
worthy of notice consists in the thumb of the hind foot 
being more developed in the Opossums ; but, compared with 
the Peramelida , the animals under consideration differ much 
in external characters, and very considerably in the structure 
of the skull. The situation of the Didelphidtv in a natural 
system, then, should be between the Dasyuridm and the 
Peramelidw , but nearer to the first of these two families. 
Genus, Didelphys. 
Didelphi* *. Linn. Syst. Nat. §. p. 71- 
Philander. Bats*. Regn. Anim. 175G. 
Didelphidec without check pouches, and in which the toes of the 
feet are free—that is, not joined by a web. 
Section I. Opossums in which the pouch is well 
developed . 
A\ e shall commence our descriptions with those species 
which are of large size, and have very long hairs interspersed 
with those which form the ordinary fur, as is the case in the 
Common Opossum of North America. 
From iU am! double utc*ru* 
