280 
POUCHED MAMMALS. 
are about the size of a mouse, after which they venture abroad, although return¬ 
ing to its shelter for the purpose of being suckled or sheltering for a considerable 
time. The female exhibits the most marked attachment to her offspring, and 
endeavours by every means in her power to prevent her pouch from being opened. 
Rat-Tailed The rat-tailed opossum (D. nudicaudata) is a well-known 
opossum. representative of the second group of the genus, which includes 
three medium-sized species, characterised by their short, close fur being of one 
kind only, and their long tails, which in two of the species are naked, although in 
the thick-tailed opossum ( D. crassicaudata ) the tail is hairy nearly to its tip. 
Although in the two species above-named the pouch is rudimental or absent, it is 
well-developed in the Quica opossum (D. opossum). 
Philander The philander (D. philander) and the woolly opossum 
Opossum. (J). lanigera) are easily distinguished from the members of the 
preceding group by the presence of a distinct brown streak running down the 
middle of the face. The pouch is represented merely by two longitudinal folds of 
skin. The philander attains a length of from 9| to 11| inches to the root of the 
tail; the tail itself varying from 12^- to 15 inches. The fur is thick, soft, and 
woolly, and of a dull yellowish or rufous grey colour, with the face pale grey, save 
for the dark brown streak down the forehead, and similar dark areas round the 
eyes; the under-parts being some shade of yellow. This species is restricted to 
Guiana and Brazil, but is replaced in most other parts of tropical South America 
by the somewhat larger woolly opossum. In both species, the young, which may 
be a dozen in number, are carried on the back of the mother, and it is marvellous 
with what rapidity the females when thus loaded manage to climb trees. 
The murine opossum (D. murina), ranging from Central Mexico 
Murine Opossum. ' ' 0 ° 
to Brazil, may be taken as an example of the fourth group of the 
genus, in which all the species are small, with short, close hair, very long tails, and 
no dark streak down the middle of the face. The pouch is absent in all the group. 
In size the murine opossum may be compared to a common mouse; the general 
colour of its fur being bright red. From their small size it may be inferred that 
all the opossums of this group live exclusively upon insects. 
Three-striped The last group of the genus includes its smallest representatives, 
Opossum. among which the three-striped opossum ( D. americana) of Brazil is 
conspicuous for its coloration. The whole ten species which constitute this group 
are shrew-like little creatures, easily recognised by their short and generally non- 
prehensile tails, which are less than half the length of the head and body. The 
three-striped species, which is by no means the smallest, measures from 4^ to 5| 
inches to the root of the tail; while the length of the tail is rather less than 
21 inches. Its general colour is reddish grey, with three black bands running 
down the back. Another species ( D. unistriata) has a single dark line down the 
back; but in nearly all the others the colour is uniform. The smallest of all is 
the shrew-opossum (D. sorex), from Rio Grande do Sul, in which the length of the 
head and body is less than 3 inches. 
Water Opossum ^he water-opossum or yapock ( Chironectes minima) differs from 
all the other members of the family in having the hind-toes webbed, 
and the presence of a large tubercle on the outer side of each fore-foot, giving the 
