272 Mr. O. Thomas on 



jiHt/wscinn/s would apjioar to be most nearly allied to 

 Hcliosciiirus, but may be distiugjuislied by its possession of 

 two uj)per premolars. As already explained in my previous 

 ])a])er, its basin-shaped lower molars se});irate it from Para- 

 uerus and Funisciunis, and its more normal skull from the 

 peculiar geuus Myrsilus. 



XXIX. — Notes on Bats of the Genus Histiotus. 

 By Oldfield Thomas. 



(Published by permission of tlie 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 

 cars. 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 ease 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. velatits, 

 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 shajie of the 



ears. 



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



