The next genus of the family Phalangistidæ contains the Flying Phalangers, which form the genus Petaurus. They have all the peculiarities of the Phalangers, and also a skin on the flank of the body, which is extended between the fore and hind legs, which serves to sustain the animal in the air, when descending from a height. They have a long hairy tail. The Yellow-bellied Flying Phalanger (_Petaurus australis_, Shaw) may be taken as the type of the genus, and is fourteen inches long in the body, and nineteen in the tail. The peculiar fold of fur, which is its flying machine, is attached to the fore leg as far as the elbow, and all down the legs to the great toe. It is common in all the brushes of New South Wales, particularly those along the coast from Port Philip to Moreton Bay. Mr. Gould states, in addition to this, “In these vast forests, trees of one kind or other are perpetually flowering, and thus offer a never-failing supply of blossoms, upon which the animal feeds. The flowers of the gum-trees, some of which are of great magnitude, are the principal favourites, and, like the rest of the genus, it is nocturnal in its habits, dwelling in holes of trees and in the hollows of branches during the day, and displaying the greatest activity at night, while running over the small leafy branches, sometimes even to their very extremities, in search of insects and the honey of the newly-opened blossoms. Its structure being ill-adapted for terrestrial habits, it seldom descends to the ground, except for the purpose of passing to a tree too distant to be attained by springing from the one it wishes to leave. The tops of the trees are traversed at a pace and with as much ease as if it were on the ground. If chased, it ascends to the highest branches, and performs enormous leaps, sweeping from tree to tree with wonderful address.” A slight elevation gives its body an impetus, which, with the expansion of its membrane, enables it to pass to a considerable distance, always ascending a little at the extremity of the leap. By this ascent the animal is prevented from receiving the shock which it would otherwise sustain. THE SQUIRREL FLYING PHALANGER.[105]