Florida, of the Nggela Group, is approximately halfway between Santa Ysabel and Guadalcanal. _Pteralopex atrata anceps_ occurs on Santa Ysabel and on Guadalcanal but is unknown from Florida. Fauro lies between Bougainville and Choiseul. _Pteralopex atrata atrata_ and _Pteropus rayneri grandis_ occur on Choiseul and on Bougainville but are unknown from Fauro. As suggested earlier, small islands like Fauro and Florida possibly cannot support large fruit bats, although they probably would utilize these small islands when in transit between larger islands. Fauro apparently is important to the distribution of the two subspecies of _Dobsonia inermis_ and _Nyctimene albiventer_ in the Solomons (see Figs. 9 and 13). In both species, one subspecies is found in the eastern chain of islands and one subspecies is found in the western chain. Specimens of _Dobsonia inermis_ from Fauro and Bougainville can be identified as the subspecies _inermis_ whereas those from Choiseul are assignable to the subspecies _minimus_. _Nyctimene albiventer bougainville_ occurs on Bougainville but specimens of _N. albiventer_ from Fauro and Choiseul can be identified as the subspecies _minor_. Although interchange of genes occurs between populations on Bougainville and Fauro in the case of _D. inermis_, the population of _N. albiventer_ on Fauro is at least partially isolated from the population on Bougainville. Rennell and Ontong Java are relatively isolated from other islands in the Solomons (see Fig. 17). Only one kind of bat (_Pteropus howensis_) is known from Ontong Java and apparently is endemic to that atoll. _Pteropus tonganus geddiei_, one of the megachiropterans that occurs on Rennell (Table 5), also is found in the New Hebrides and on New Caledonia (Table 4). This makes _P. t. geddiei_ the only megachiropteran bat in the Solomons that is more closely related to bats on islands to the southeast of the Solomons than to bats on other islands of the Solomons, the Bismarcks, or New Guinea, to the north and west. The other species of megachiropterans (_Dobsonia inermis_ and _Pteropus rayneri_) on Rennell are found also on other islands in the Solomons. It is to be noted that Mayr (1931) regarded the avifauna of Rennell as most nearly like that of the New Hebrides and New Caledonia. He suggested that the prevailing winds from the southeast have been important for birds that have reached Rennell. The New Hebrides and New Caledonia are four and a half times farther from Rennell than are San Cristobal and Guadalcanal. On first consideration a person might doubt that the winds would be favorable enough to compensate for the great distance between Rennell and the New Hebrides and New Caledonia. Darlington (1938) has used the formula X n/m to obtain a comparison of barriers of different widths. [X = the probability of an individual crossing a barrier of width m; the probability of an individual crossing a similar barrier of width n