CHIROPTERA 39 



Natterer's Bat are not born until about the last week of June. 

 On the other hand, Mr Coward had a young Water Bat with a 

 forearm of only 20 mm., and a total expanse of only 1 10 as against 

 220 in the adult, taken on the wing on 28th June, and on the 

 same day a female which appeared to have recently given birth, 

 while I have examined a young Pipistrelle and Whiskered, fully 

 grown but immature, on 9th August and 26th July respectively. 



As stated above, the breeding habits of the various species 

 probably vary with the degree of torpor which they undergo 

 during hibernation and the climate of the locality in which they 

 exist. The most simple are those of bats like Leisler's, which 

 hardly fly at all during the winter. Others which, like the 

 Pipistrelle, fly at intervals throughout the year, probably have 

 a lengthened breeding season and may copulate frequently. 

 But even if they do, Messrs Rollinat and Trouessart find that 

 there is no fecundation until the spring. 



The facts as observed in Britain seem difificult to reconcile, 

 unless either copulation takes place in spring, or the commence- 

 ment of gestation is retarded by a damp climate, just as it is 

 hastened by warmth. 



The birth of bats in captivity has been independently 

 observed in England by Daniell and Mr Whitaker for the 

 Noctule, and by the latter naturalist for the Pipistrelle. These 

 observers were only able to approximate the period of gesta- 

 tion at not less than thirty-eight days for the former and 

 about forty-nine days for the latter species, so that as far as 

 they go they do not disagree with Messrs Rollinat and 

 Trouessart. They find, however, that the young may be born 

 head first. In one case the mother hung in the normal position 

 head downwards ^ ; in the other this position was reversed. 



Many naturalists, from Spallanzani downwards, have referred 

 to a supposed preponderance in numbers of the female sex. On 

 this point no satisfactory evidence is forthcoming, but the 

 apparently superfluous size and capacity of the male generative 

 organs would be accounted for if it could be shown that bats 

 are polygamous. 



1 Sir H. A. Blake {Set. Proc. Roy. Dublin Soc, IV., N.S., 449-45°. 1885) observed 

 the birth of an Indian fruit-bat, in this case also feet first. Professor Robert Collett 

 writes me that he has observed parturition once each in Daubenton's and Nilsson's 

 Bats. The mother in each case hung head downwards. 



