184 VESPERTILIONID^. 



among the genera of Chiroptera. The common Bats of all countries, 

 especially of those lying within the temperate and subtropical 

 regions of the northern hemisphere, generally belong to it. The 

 characters of the species often vary considerably within certain 

 bounds ; and specimens of the same species, even from the same 

 locality, occasionally present differences which lead to their being 

 regarded as examples of-distinct species. 



The colour of the fur is generally dark brown or black, the 

 extremities of the hairs of a paler colour on the upper surface and 

 ashy or whitish beneath. 



Bange. Generally distributed throughout all regions of the earth, 

 but more common in the temperate and subtropical regions of the 

 eastern hemisphere. The species of this genus have also the most 

 northerly range, and one, Vesperiu/o borealis, has been found close 

 to the limits of the Arctic Circle. 



Synopsis of Subgenera. 



2—2 



A. Incisors -g-. 



a. Outer upper incisors well developed, or 



if small, yet distinct ; no bone in 

 the penis. 

 a'. Lower premolars 2 — 2. 



a". Upper premolars 1 — 1 1. Vesperus, p. 184. 



b". Upper premolars 2 — 2 2. Vespbbugo, p. 209. 



6'. Lower premolars 3 — 3 3. Lasionycteeis, p. 238. 



b. Outer upper incisors very small, scarcely 



raised above the gum, occasionally 

 posterior to the tooth-row ; penis 

 with a distinct bone. 



c". Premolars ^ 4. Hespeboptenus, p. 239. 



B. Incisors -^. 



d". Premolars gEi 5- Rhogeessa, p. 245. 



e". Premolars ^—^ 6. Scoxozotrs, p. 243. 



2 2 



Inc. -g-, the outer incisors generally/ much shorter than the inner ones, and 



in a plane anterior to them ; pm. 2—21 ^^ upper premolar large, close 

 to the canine : postcalcaneal lobe narrow : tuings frotn the base of tlie 

 toes ; the last, or the two last caudal vertebra generally free. Hab. 

 Eastern and western hemispheres. Subgen. Vbspebus. 



Synopsis of the Species. 



A. Thumbs and soles of the feet simple, 



without adhesive cushions. 



a. Eai's longer than the head, auditory 



bidlcs ossece very large. 



a'. Tragus long, attenuated upwards 



and inclined outwards, reaching its 



greatest width below the middle of 



