1917.] Lang and Chapin, Distribution and Ecology of African Chiroptera. 481 



persal of flora and fauna to such a degree that uniformity, one might almost 

 say monotony, has become the hall-mark of this great forested complex. In 

 later years botanists have confirmed the view that in spite of its luxuriant 

 diversity of forms the flora of this rain-forest in its general composition is 

 fundamentally the same over its entire extent. Many of its important 

 elements are even represented far beyond its confines, in the wooded ex- 

 tensions along the larger affluents of the rivers draining the territory. 



As shown previously, fruit-bats are naturally more common in regions 

 covered by rain-forest, where fruit ripens throughout the year, than in 

 more arid regions, where such fruit-bearing trees as furnish food for these 

 bats are rarer and one crop of fruit is the rule. These latter regions have 

 well-marked rainy and dry seasons. Fruit is naturally scarcest after the 

 annual fires have slowly eaten across the country and left the shrubs and 

 trees leafless and the fields in such a barren condition that a comparison with 

 the effects of heavy frosts in temperate climates suggests itself. Within a 

 very short time the grass sprouts again and flowers often cover the trees 

 before the leaves have appeared. It is of great importance that only a few 

 degrees north of the equator the seasons happen to be the reverse of what 

 they are at that time south of the equator. Furthermore the essential 

 elements of the flora remain nearly the same over the entire eastern and 

 southern Ethiopian sub-regions. Thus the fruit-bats of these districts, by 

 adjusting their migratory flights, might easily escape the unpleasant and 

 otherwise inevitable conditions of an annual famine. In fact the power 

 of flight could bring them within the fragrance of ripening fruit throughout 

 the year, if they but chose to travel across country between 5° south and 

 5° north of the equator. Such migrations are wholly within the powers 

 of fruit-bats. Since fruits are not always equally plentiful, they have 

 to shift continually even in the rain-forest. They have nowhere well 

 established roosts, nor are they present in numbers for a long period in 

 any region except where cultivation of non-autochthonous fruit-trees helps 

 provide an ample food-supply throughout the year, as in many eastern and 

 western coastal districts. Though no positive observations with regard 

 to regular migrations are on record and only "large flights" and "great 

 numbers," without date or locality, are found in the descriptions of various 

 travelers, the occurrence of several species (Eidolon hchum, Roussettus 

 leachi, Roussettus cegyptiacus, Epomophorus wahlbergi, Epomophorus anurus) 

 across the eastern and southern portion of the Ethiopian subregion would 

 be a good reason to suggest migration as the only possible solution of 

 their presence throughout the entire territory, where they would have to 

 starve should they remain in one region throughout the year. 



The following detailed notes on the species collected by the Congo 



