1917.] Lang and Chapin, Distribution and Ecology of African Chiroptera. 483 



fifth rather short, thus forming a long and narrow wing, much better suited 

 for its long flights. In epomophorine bats, however, the fourth and fifth 

 digits nearly equal the third; the resulting broad wing intimates, as we have 

 often observed, that their flight is more irregular. A rather heavy wing 

 adapted for relatively slow flight is characteristic of all fruit-bats; the 

 membranes are never transparent, but usually dark, — brown or almost 

 black, — yellowish only in Casinycteris. These membranes are very ex- 

 tensible. They are folded around the body not only as a protection against 

 the rain but also, when hanging on leafless branches by the hundreds 

 (Eidolon helvwn), to shield the eyes against the glaring sun. 



The tail is either much reduced or totally missing, and instead of a 

 continuous caudal membrane we find only rudimentary borders along the 

 inner side of the legs. Thus they are devoid of any such efficient steering 

 apparatus as that which a long tail supporting a large membrane would 

 offer, and have only their long legs to rely upon for turning. With them 

 flight is only a means of travel from tree to tree to secure fruit and is not 

 needed for the rapid and eager pursuit of fast-flying prey, so great a neces- 

 sity to all insectivorous bats. The comparative simplicity of the outer 

 ear, and the lack of highly developed sense organs in their wing-membranes 

 are noteworthy facts. Contrary to the behavior of insectivorous bats the 

 larger fruit-bats, when let loose in a room, fly against obstacles and windows 

 with the same injurious effects as birds. 



Sexual characteristics are, as a rule, more pronounced in fruit than in 

 insectivorous bats. The larger size of the males (p. 502), the huge ossified 

 larynx (pp. 501 and 505), and the glandular patches of conspicuously colored 

 hair (p. 512), will be mentioned in the notes under the various species. 



Since fruit forms their only food, it is hardly possible that their eyes 

 alone, though relatively large, should suffice to discover it, especially as 

 much of the wild fruit is hidden beneath the dense canopies of the larger 

 trees. Their great flights, resembling migrations, have been pointed out 

 under notes on the various species and are undoubtedly undertaken in 

 search of ripe fruit. From our observations we feel sure that their sense of 

 smell is very highly developed and our experiments show that it is probably 

 their principal guide, since the fragrance of ripe fruits is often very strong. 

 In nearly all fruit-bats the nasal region is extremely long, with well-developed 

 ethmoids as a special provision for the highly sensitive organs of smell. 

 The large olfactory lobes (Fig. 20, p. 507) also show that smell with them is 

 a very important factor. 



The skull with very few exceptions (p. 511) is elongate and rather smooth 

 in outline. The brain-cavity is comparatively small, a certain sluggish- 

 ness in temper and action distinguishing them from the more active in- 



