36 INTRODUCTION 



daylight may be seen between its body and that of its 

 mother. 



The young grow rapidly, soon acquire hair, and are always 

 strong and vigorous. Their eyes open between the fourth and 

 ninth day,^ most usually on the fifth or sixth. Between the 

 ninth and thirteenth days they begin to leave their mothers 

 and divide their time between hanging by themselves and 

 attachment to the nipple under the cover of the maternal wing. 

 Probably after the second week the wild female leaves her young 

 one at home when she flies abroad to feed, but takes it under 

 her wing on returning. In fact, Mr Whitaker found that a 

 young Pipistrelle soon became a burden which was carried in 

 flight only with difficulty, and seriously impeded the feeding of 

 its mother on a flat surface, especially when she attempted to 

 " pouch " her food. 



On the twelfth day a young Mouse-ear had attained an 

 expanse of nearly 250 mm., and was well covered with hair. 

 The permanent teeth were already replacing those of the 

 milk dentition. A few days later it no longer sought its 

 mother's wing, even when being suckled, but stretched itself 

 frequently and expanded its wings. 



By the thirtieth to thirty-fifth day the milk dentition had 

 disappeared, but the young one was not finally weaned until it 

 was about two months old. In the wild parties the young were 

 nearly as big as their dams in July, and the nursing colonies 

 broke up before the end of August. Other species probably vary 

 in these respects, since wild Notched-ears ^ were found to have 

 finished lactation on 26th August, whereas young Euryale Horse- 

 shoes, nearly equalling the adults in size, but with stomachs full 

 of milk, were on the wing only on the i8th of the same month. 



Some naturalists have stated their belief that the females 

 suckle the young promiscuously,^ but, except in the case of the 

 Lesser Horseshoe, Messrs RoUinat and Trouessart, after many 

 years of research and experiment, find no evidence of this. Mr 

 Whitaker's report on two Pipistrelles is similar. 



The above observations may probably be regarded as 



■ Whitaker gives the eighth day for the Pipistrelle and twelfth for the Noctule. 



" My Otis emarginatus. 



^ E.g., Osburn, in the case of a captive Monophyllus, op. cit, 84. 



