MAMMALIA 363 



have been distinguished, but lack of space forbids a detailed de- 

 scription of them. 



Order 2. Dermoptera. — This is an order containing but a single 

 species, Galeopithecus volans (Fig. 187), the so-called "fljdng lemur." 

 It is a bat-like creature, nearly as large as a cat, with membranes 

 stretched between the fore and hind legs, also between the head and 

 the hand and between the tail and the hind feet. In certain respects 

 it seems to be intermediate between the insectivores and the bats. 



Order 3. Chiroptera (Bats). — Bats may be defined as true flying 

 mammals in which the fingers of the fore limb are greatly elongated 

 to support, hke the ribs of a fan, a membraneous airplane. They do 

 not merely soar or parachute like the flying lemur or the flying squir- 

 rels, but actually propel themselves with rapid wing strokes as effec- 

 tively as do many of the birds. Extra planing surface is acquired 

 by a stretch of membrane running from the hind limbs to the tail. 

 The knees of bats are turned backwards, a position that would require 

 dislocation of the hip in any other mammal. Many of the bats have 

 large dehcate ears and extremely complicated folds of sensitive mem- 

 brane surrounding the nostrils (Fig. 188, B, C, D) ; these are believed 

 to be organs of a sixth sense (kinsesthetic sense) that gives warning 

 of the nearness of solid objects in the dark. It is said that bats liv- 

 ing in caves that have absolutely no light, fly about in swarms at a 

 high speed and never collide with one another nor with the walls 

 or roof of the cave. Bats are divided into two sub-orders: Micro- 

 chiroptera and Megachiroptera. 



Sub-Order 1. Megachiroptera (Fruit-eating Bats). — These are rather 

 large animals and are sometimes called "flying foxes." They occur, 

 in India, Australasia, Ceylon, Africa and Madagascar. The best^ 

 known is Pteropus, a large bat with a wing-spread of over five feat, 

 though the body is only about a foot in length. Their main food con- 

 sists of figs and guava. They are distinctly social in habit and move 

 about in droves of considerable size. Another well-known species 

 is the collared fox-bat (Xantharpyia collaris) which is shown in its 

 customary resting position with its young clinging to its abdomen 

 (Fig. 188, A). 



Sub-Order 2. Microchiroptera (Insectivorous Bats). — These are 

 small bats (Fig. 188, B) with practically cosmopolitan range on ac- 

 count of their great powers of flight. At least five hundred species 

 are known. They are decidedly nocturnal in habit, taking up the 



