50 THE FLYING FOX, ETC. 



doubtless for the same reason that in the human infant the 

 liver is specially large to aid to digest the excess of hydro- 

 carbons in a milk diet, fats, and sugar. The heart and lungs 

 are specially developed to sustain long flight and rapid motion, 

 and to this same end the thoracic muscles are powerful and 

 large. In land-resting mammals the hind limbs, the legs and 

 leg muscles are specially strong for walking and running, but 

 in the Chiroptera the fore limbs are specially developed for 

 aerial progression. In the flying-fox the forearm is strengthened 

 by a strong curved radius ; the ulnar is rudimentary ; the palms 

 and fingers are specially fitted for grasping. The hind limbs 

 are proportionately minimised. The wing membranes, resembling 

 thin gutta-percha sheeting, are attached between the fore limbs 

 and the body, and "in the different species spread out by the hind 

 limbs and more or less along the tail, but the interfermoral margin 

 is deeply emarginate, and in some species scarcely developed in 

 centre. The bones are hollow for lightness, as the huge 

 Pterodactyls of the Oolite periods. 



All the species are covered with a longer or shorter fur, 

 which in its colouration is protective. The bats, which roost in 

 cracks and crevices, or hang from roofs in dark caves, need little 

 further protection, and are uniform and sombre -coloured. The 

 flying-foxes, which hang in company from trees, have the head 

 and neck more or less red, or yellowish, or grey ; and to instance 

 the one species which rests at certain times round the leaf-stalks of 

 the cocoanut palm — this colouring makes them resemble the 

 bunches of ripening cocoanuts. 



The early life history is not well known. The penis is 

 strengthened by a distinct bone. As far as known, the young are 

 brought forth alive. They are suckled on two teats. It is stated 

 that as many as five are produced at a birth. The smallest 

 discovered in Australia were about an inch and a-half long. 

 One observer living in a bush house says that he noticed under 

 the eaves of the roof what he took to be some mud-cell 

 domiciles of the lai-v(c of hornet-wasps. On sweeping them down, 

 he was surprised to find them to be young flying-foxes. The old 

 ones had been noticed coming in and out. These young ones 

 were hanging in the usual way by their claws. Other observers 

 have noted that when the parents were suddenly startled from 



