1452 THE POUCHED MAMMALS, OR MARSUPIALS 



six to sixteen in a litter. They remain in the pouch till they are about the size of 

 a mouse, after which they venture abroad, although returning to its shelter for the 

 purpose of being suckled or sheltered for a considerable time. The female ex- 

 hibits the most marked attachment to her offspring, and endeavors by every means 

 in her power to prevent her pouch from being opened. 



P _ .. The rat-tailed opossum ( D. nudicaudata) is a well-known repre- 



Opossum sentative of the second group of the genus, which includes three 



medium-sized species, characterized 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). 



The philander ( D. philander} and the woolly opossum ( D. lani- 

 gera) 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 nine and one-half to eleven and one-half 

 inches to the root of the tail; the tail itself varying from twelve and one-half to fif- 

 teen inches. The fur is thick, soft, and woolly, and of a dull yellowish or rufous- 

 gray color, with the face pale gray, 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 of 

 the 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 marvelous with what rapidity the females when thus loaded 

 manage to climb trees. 



The murine opossum {D. murina}, ranging from 'Central Mexico 

 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 color ( of its fur being bright red. From their small size it may be in- 

 ferred that all the opossums of this group live exclusively upon insects. 



The last group of the genus includes its smallest representatives, 



among which the three- striped opossum ( D. americana) of Brazil is 

 Opossum 



conspicuous for its coloration. The whole ten species which constitute 

 this group are shrew-like little creatures, easily recognized by their short and gen- 

 erally nonprehensile 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 

 four and one-half to five and one-fourth inches to the root of the tail; while the 

 length of the tail is rather less than two and one-half inches. Its general color is 

 reddish gray, 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 color 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 three 

 inches. 



