1917.] Lang and Chapin, Distribution and Ecology of African Chiroptera. 489 



helvum, the only fruit-bat we found hanging up in clusters, has short, some- 

 what glossy hair different from our other fruit-bats. 



These features seem so important a characteristic that one can set apart 

 nearly all the other bats that have loose, rather long and sometimes frizzled 

 hair. These hang perpendicularly, suspended by only the claws of their 

 hind limbs, each one by itself. Sometimes they live in hollow trees and 

 form colonies (Hipposideros langi) but never huddle together in bunches. 

 Caves or houses may shelter them in great numbers (Hipposideros abce, 

 Hipposideros caffer). Others hang one by one on branchlets {Lama frons 

 affinis) or hide in dense clusters of leaves (Eptesicus faradjius, Glauconyc- 

 teris papilio), or rest in the vegetation of swamps beneath the crown of 

 papyrus (Nycteris pallida). One would include in the long-haired groups 

 also such solitary bats as Kerivoula cuprosa and Pipistrellus musciculus, 

 that crawl into knot-holes, and those that seek refuge in bunches of plan- 

 tains (Pipistrellus nanus, Myotis bocagii). 



A few remarks on certain conditions in these territories which especially 

 influence the food-supply of insectivorous bats will probably add to the 

 better understanding of their life-histories. 



The equatorial rain-forests with their moist, even temperature of about 

 100°, changing as little in the lapse of 24 hours as during a twelvemonth, 

 offer conditions to them that could hardly be more favorable. Neither the 

 bats nor the insects upon which they feed have there to submit to such 

 inhibitory influences as would be caused by hibernation or estivation. The 

 great humidity also prevents such catastrophes as the spreading of fires. 



The forested galleries are like promontories pushed far out into the drier 

 regions, where annual grass-fires have stunted the growth to such an extent 

 that the large hollow trees in these moist tracts or along the rivers represent 

 the only opportunities for roosting. The vicinity of water, especially the 

 open sheets with their abundance of crepuscular insect-life, are undoubtedly 

 an invaluable adjunct. These forested belts also act as an effective barrier 

 against the destructiveness of the grass-fires and, being the only luxuriant 

 places amidst the scorched fields, they become a haven of refuge for millions 

 of insects. 



The open country or bushveldt, with grass growing to a height of 5 to 

 14 feet, has 15 to 25 percent of its surface covered with bushes and low trees; 

 usually not attaining more than 30 feet in height. A few still larger ones 

 are scattered widely between. Shortly after the end of the rainy season, 

 in December and January (in the northeastern Congo basin), the impeding 

 and now useless minor vegetation is set on fire as an annual house-cleaning. 



To insectivorous bats such extensive grass-fires mean wholesale destruc- 

 tion of their food-supply. Millions of insects are then wiped out. Small 



