25 
The Ursidce , or Bears, all walk on the sole of the foot, or 
are what is termed plantigrade , and with the exception of the 
Grizzly, climb trees with great facility. The diet is much 
mixed, being indiscriminately animal or vegetable. 
They are distributed throughout the Northern Hemisphere 
—but one true bear having yet been found south of the 
equator. 
The Common Opossum (. Didelphys virginiand) ranges east 
of the Missouri river, from about the latitude of lower Mas¬ 
sachusetts to the Gulf of Mexico, and with its congener ( Di - 
delphys californicd ), which replaces it west of those limits, 
represents in North America the order of marsupials. (See 
page 43.) The opossums belong to the carnivorous branch 
of the order, although their diet is very varied, consisting of 
small birds, mammals, reptiles, and eggs, as well as of fruits, 
buds, and grain. 
They live generally in the hollow of a tree, where the 
female produces as many as fifteen young at a time, breeding 
several times in the course of a year. The characteristic 
pouch of the order is well developed in these animals. 
They have a very prehensile tail, and are also distinguished 
by the peculiarity of their dentition, which consists of ten 
incisors, two canines, and fourteen molars in the upper, and 
the same, with two incisors less, in the lower, jaw, or fifty 
teeth in all. 
A number of Opossums are found in South America, more 
or less resembling this species. 
The Condor {Sarcorhamphus gryphus) is the largest of the 
Vultures, rivaling and even exceeding in size the Bearded 
Vulture or Lammergeyer of the Alps. 
They do not build nests, but commonly live in pairs on the 
bare rock, high up among the lofty peaks of the Andes, from 
which they soar to a height almost beyond the range of human 
vision, plunging down only when their keen sight discovers 
the carcass of some dead animal on the plains below. They 
live mostly on carrion, but when pressed by hunger, it is said 
that several of them will sometimes band together, to attack a 
young calf or a disabled animal out of the herd, and with 
blows of their powerful beaks and claws destroy it. The 
sexes may be distinguished by a short ruff of soft feathers, 
which invests the neck of the adult male. 
