CHIROPTERA 19 



between adults at different seasons of the year, have been little 

 studied, and nothing is definitely known as to how the fur is 

 moulted. Usually the immature pelage is more uniform, due to 

 absence of grizzled hair tips, but it may be either darker or 

 lighter than that of the adult. In young Natterer's and 

 Whiskered Bats the ventral and dorsal surfaces are more 

 strongly contrasted in coloration, while the first coat of young 

 Horseshoes is recognisable by its grey tint. 



Secondary sexual characters, other than those of colour, 

 are commonly found amongst exotic bats, the males of which 

 exhibit many remarkable glandular structures.^ The measure- 

 ments given in this work suggest that the wings of females are 

 on the average larger and the animals themselves heavier than 

 the males. 



Variations other than those of colour are still in need 

 of attention, and further study may reveal the presence 

 of local distinctions at present unknown. Meanwhile it 

 has been shown that both the British Horseshoes are on 

 the average slightly smaller than those of the neighbouring 

 continent ; the same may prove to be true of the Long-eared 

 and, I suspect, also of the Barbastelle. The British Bechstein's 

 Bat also presents some differences, but this bat is so little 

 known that the nature of its variations is obscure. 



Abundance and geographical distribution: — Outdoor know- 

 ledge, no less than museum study, has advanced haltingly, 

 and all the more so since bats, like cetaceans, are the bane of 

 some writers on geographical distribution, the possession of 

 wings in the one case and of swimming equipment in the other 

 having apparently convinced them that both orders must be 

 exempt from the laws governing the distribution of other 

 mammals. This error, combined with ignorance of distinguish- 

 ing characters, has in the past led to much confusion of species 

 and incorrect notions as to their relative numbers. Locally 

 abundant bats such as Leisler's, and others so common and 

 widely distributed as the Whiskered, have shared a reputation 

 for rarity with Bechstein's, while Natterer's, Daubenton's, and 

 the Barbastelle have been surrounded with much unnecessary 

 and mysterious obscurity. 



1 See also Osburn, op. cit. infra, 77. 



