SYSTEM OF NATURE. 
71 
dog; their pace is almost without exception a series of 
leaps. The fore legs also indicate, in many instances, a 
disposition to be diverted from their normal employ — that 
of progressive motion—and to assume the office of hands : 
the squirrel and dormouse take a nut with their fore feet, 
as with hands, and thus hold it firmly while they gnaw an 
aperture with their teeth : mice, rats and arvicoles, do 
exactly the same with the various descriptions of food 
which they prefer : rabbits and hares, for a long time to¬ 
gether, will stand on their hind legs, and listen or look 
about if fearful of danger. The jerboas perhaps offer the 
most striking exemplification of these characters. 
This saltant character, combined as it is with the pre¬ 
ponderating employment of the posterior legs, seems most 
decidedly to distinguish the whole class of marsupials. 
The kangaroos are apparently the normal group, and how 
obviously do they exhibit the character in question. Even 
in those animals which to all appearance are not formed 
for leaping, the inferior surface of the planta is perfectly 
bare and callous throughout its entire length, as if with 
constant attrition against the earth. I do not even wish 
to exclude the w r olf-like Thylacinus, almost invariably 
stuffed and drawn in a digitigrade position. Let me 
recommend those who wish to controvert this opinion con¬ 
cerning the proximity of the Glires and marsupials, to take 
a glance at any tolerably extensive collection of the latter, 
and the very contour of the animals will be enough to 
convince them. 
2ndly. Volitantia. “ The Cheiroptera, [omithoid pla- 
centals] or bats, have the arms and fingers excessively 
long, forming with the membrane which occupies their 
intervals true wings, possessing even a greater extent of 
