268 VESPERTILIONID^. 



Interfemoral menibraiie more or less densely covered with Juiir on its 

 upper surface. In some species the -whole of the upper surface of 

 the interfemoral is densely clothed with fur, which also extends 

 upon the wing-membrane for a considerable distance, and passes 

 outwards in- a broad band behind the forearm to the carpus (see 

 Plate XVI. fig. 1). 



Dentition. Inc. i^, c. j^, pm. ~ or i^i, m. j=|. 



Upper incisors unicuspidate and acutely pointed, close to the 

 canine on each side, directed forwards and inwards. In the species 

 with two upper premolars the iirst premolar is very small, and is 

 placed in the inner angle between the closely approximated canine 

 and second premolar. Skull broad and flat, frontal bone slightly 

 grooved (Plate XVI. fig. Irt). 



Range. The Nearctic and Neotropical Regions, from Canada to 

 Southern Chili. 



The species of this genus with a single upper premolar agree in 

 the number of their teeth with Nycticejus, and also with Scotophilii-s, 

 which is limited to the Eastern Hemisphere, but are easily recognised 

 by the peculiar form of the ears and especially of the tragus, and by 

 the distribution of the fur. 



The relative development of the minute first upper premolar has 

 been used to distinguish some forms ; but it is evident that, in a genus 

 where this tooth is altogether absent in certain species, its relative 

 size in those species which possess it can scarcely be considered of 

 sufficient importance to lead to the formation of new species. 



Syiiojjsis of Subgenera and Sjpecies. 



2—2 



I. Premolars ^^^ ; the whole upper surface 



of the interfemoral membrane clothed 



with hair Siibgen. Atalapha. 



a. Forearm quite naked ; fur reddish ashy 1. A. noveboracensiSf-p.'iQQ. 



b. Forearm with a small patch of hairs 



near the elbow ; fur generally brown- 

 ish ashy 2. A. cinerea, p. 272. 



II. Premolars jrrjj the posterior half or third 



of the interfemoral membrane naked . . Subgen. Dasyptertjs*. 



c. The posterior third of the interfemoral 



naked. 



a'. Tragus obtuse, curved inwards ; fur 



olive-brown 3. A. intermedia, p. 274. 



b'. Tragus subacute, straight, the tip 

 only curved inwards ; fur bright red- 

 dish 4. A. ej/reyia, p. 27.5. 



d. The posterior half of the interfemoral 



naked, 

 c'. Tragus subacute, curved inwards ; 



fur pale yellowish brown 5. A. ega, p. 270. 



* Basyplerus, Peters, MB. Akad. Berl. ]870, p. 904. 



