86 OLDFIELD THOMAS 



the wing-membrane external to the same line is pure white 

 above and below, contrasting very markedly with the dark skin 

 of the limbs and digits. 



Number of teeth strictly as in Scotophilus. Upper incisors long, 

 slender, unicuspid, close to the canines ; without posterior ledges, 

 but each with a very minute postero-external basal cusp. Lower 

 incisors tricuspid, overlapping, placed at right angles to the 

 direction of the jaws. Anterior lower premolar not as in Scoto- 

 philus, crushed in between the posterior one ■ and the canine, but 

 more as in Vesperugo, long, as long as the posterior one, and 

 quite as large in section basally, its long simple cusp directed 

 somewhat outwards, out of the general line of the teeth. 



Measurements o^ the type, an adult male, preserved in spirit: 



Head and body 50 mm. ; tail 31 ; head, length 17, breadth of 

 muzzle across eyes 10.8 ; ear, length above crown 8.8, from base 

 of outer margin 14.5; tragus, length of inner margin 2.0, of 

 outer margin 3.7; forearm 31 (= 1.22 in.); lower leg 12; hind- 

 foot without claws 7.1 ; calcaneum 13. 



Hab. Bathurst, River Gambia. Collected by D.^" Percy Rendali. 



This species may be readily distinguished from all its allies 

 by its white wings, which contrast very markedly with the dark 

 coloured body and limbs, all the other known members of the 

 genus having the body and wings more or less uniformly co- 

 loured. In this respect the bats of the Gambia present rather 

 a remarkable instance of geographical isomorphism, a consi- 

 derable proportion of the smaller forms, belonging to several 

 different genera, being dark with white wings, a style of colo- 

 ration comparatively rare elsewhere. 



D.' Rendali is to be congratulated on his discovery of this 

 striking species, which forms a worthy companion to the Vespe- 

 rugo (Vesperus) rendalli described by me last year (}). 



The characters of Scotophilus albofuscus add still further to 

 the difficulty of properly distinguishing the genus Scotophilus from 



(1) Ann. Mag. N. H. (6) III, p. 362, 1889- 



