750 MARSUPIALIA. 



The OPOSSUM, Didelphys Virginiana (Plate LXII) is about the size of 

 a large cat. They have the thumbs opposable and nailless, the tail gen- 

 erally bare and prehensile for its terminal half, or more. The mouth 

 is provided with fifty teeth. They sally out at twilight or at night to 

 feed on small quadrupeds, birds, eggs, insects, molluscs, and even fruits 

 or young vegetable shoots, from which they suck the sap. The females 

 are remarkably prolific ; they have from ten to fifteen young at a litter, 

 and nurse their progeny with tender solicitude. The Opossum being 

 plantigrade, walks and runs awkwardly, but climbs well. 



Merman's Opossum, Didelphys dorsigera (Plate LXII), has no true 

 pouch, the place being indicated only by a fold of skin. The mother 

 carries her young on her back, where they cling tightly to her fur with 

 their feet, and twine their tails around hers. It is a very small animal, 

 measuring when full-grown only six inches from the nose to the root 

 of the tail. The fur is very short, and of a pale grayish-brown on the 

 upper portions. Round the eye is a deep brown mark, the forehead, 

 cheeks, limbs, and feet are of a yellowish-white, inclining to gray. Its 

 native country is Surinam. 



The Crab-eating Opossum, Didelphys cancrivora, is not so large an 

 animal as the Virginia Opossum, being only thirty or thirty-one inches 

 in total length, the head and body measuring sixteen inches, and the tail 

 fifteen. It can also be distinguished by the darker hue of its fur, the atten- 

 uated head, and the uniformly colored ears, which are generally black, 

 but are sometimes of a yellowish tint. It is peculiarly fitted for dwelling 

 in trees, where it swings with its prehensile tail. 



GENUS CHEIRONECTES. 



The Yapock, Cheironectes yapock (Plate LXII), is the only species of 

 the genus. It may be considered as the Marsupial representative of the 

 Otter. 



The general hue of the fur is a pale fawn-gray, with a very watery 

 look about it, and set closely upon the skin. Four dark bands of sooty- 

 black are drawn across the body in a peculiar, but extremely variable 

 manner. The hind-feet are furnished with a membranous web. The 

 claws are small and weak, and the thumb-joint is not opposable to the 

 others. The ears are moderate in size, sharp, and pointed, and the head 



