OPOSSUMS. 
281 
certain amount of the dark tint on the outer surfaces of the limbs, the under-parts 
being pure white. The female possesses a complete pouch. In habits the yapock 
closely resembles an otter, to which group of animals it was indeed referred by the 
earlier naturalists. Its food consists of crustaceans, small fish, and other aquatic 
animals. 
Extinct Marsupials. 
From their low degree of organisation it would be expected that Marsupials 
are some of the oldest of mammals; and this expectation is borne out by the 
facts. So far as can be determined, no placental mammals are known to have 
appearance of a sixth digit. This animal ranges from Guatemala to Brazil, and 
is distinguished by its peculiar coloration and aquatic habits. The fur is short and 
close, and the long tail naked and scaly for the greater part of its length. The head 
and body measure about 14 inches in length, and the tail about 15£ inches. The 
ground-colour of the fur is light grey, upon which there is a blackish brown stripe 
running down the middle of the back, and expanding into large blotches on the 
shoulders, the middle of the back, the loins, and rump. The face has also blackish 
markings, with an imperfect whitish crescent above the eyes; while there is a 
water-opossum (J nat. size). 
