272 Mr. O. Thomas on 



JEthosciurus would appear to be most nearly allied to 

 Heliosciurus, but may be distinguished by its possession of 

 two upper premolars. As already explained in my previous 

 paper, its basin-shaped lower molars separate it from Para- 

 aerus and Funisciui'us, and its more normal skull from the 

 peculiar genus Myrsilus, 



XXIX. — Notes on Bats of the Genus Histiotus. 

 By Oldfield Thomas. 



(Published by permission of the Trustees of the British Museum.) 



The members of the genus Histiotus are all extremely 

 closely allied to each other, their respective sizes, skulls, 

 and teeth being almost identical, and the only distinguishing 

 characters lying in the colour and the size and shape of the 

 ears. Even these latter are both somewhat variable and 

 very difficult to use for discrimination owing to the effect on 

 them of shrinkage, whether in spirit or dry. 



In 1875 * Peters wrote an account of the genus which was 

 wonderfully good, considering the comparatively few speci- 

 mens he had available. He gave excellent figures of the 

 ears of certain of the forms, these figures being referred 

 to below. In the case of the extreme southern species, 

 however, H. magellanicus, the ears are drawn much 

 too small, owing to their having been drawn from dried 

 specimens. 



As Peters pointed out, the Brazilian species, H. velatus, 

 Geoff., is readily distinguishable from all the others by 

 its more triangular ear, which has a prominent rounded 

 lobe in front projecting forwards, as shown in his plate, 

 figure 1, and is connected with its fellow of the opposite 

 side by a transverse band about 3 mm. in height. 



In colour H. velatus is very dark brown, with com- 

 paratively dark ears and membranes. Its skull is a little 

 narrower than in other species, with narrower interorbital 

 regions and palate, but the difference is really very slight, 

 considering the essential difference in the shape of the 

 ears. 



* MB. Ak. Berl. 1875, p. 785, plate. 



