8o VESPERTILIONID^— NYCTALUS 



exceeds thirty-eight days. To these should probably be added 

 another eleven,^ so as to complete the seven weeks laid down 

 by continental naturalists, but corroboration is still needed for 

 this country. The most usual time for the birth of the young 

 is evidently late in June. Thus Mr H. J. Charbonnier found 

 within the body of a female killed in June a young one having 

 an expanse of wing of 3J inches, and Mr Oxley Grabham ^ 

 writes me that he has received one, a dark, leathery-looking 

 object, just beginning to show indications of fur (and there- 

 fore at least fourteen days old), on i6th July. Gurney 

 informed Newman ^ that he once disturbed a colony of females, 

 many of which had half-grown young ones with them, and 

 he observed that when the mothers flew away, the young ones 

 clung to their under sides, and seemed to be carried without the 

 slightest inconvenience to mother or young. On the other 

 hand, Mr Whitaker took a ten days' old youngster from a hole 

 in a tree, where it remained after the departure of the adult 

 members of the colony, including its mother, so that it i% ; 

 evident that the young may either accompany their parents 

 when flying, or, when they have grown inconveniently heavy, 

 may remain suspended in the den (Plate III., p. 58). Whatever 

 else be the case, it is evident that the young must grow so 

 rapidly as to shift for themselves at an early date, and thus 

 relieve their mothers from burdens so tiresome. The increased 

 numbers which have been noticed in August, as by Mr Jeffrey 

 writing to Newman,* may probably have represented the influx 

 of the newly-fledged young, and Noctules exhibit marked dis- 

 agreement in size at this season. 



Although there is only one published instance for Britain 

 of the production of more than a single young one at a birth, ^ 

 the statements of continental writers ^ are quite clear that fami- 

 lies of two have frequently come within their experience, a 

 remarkable instance of fertility, varying with locality, which is 

 discussed elsewhere (p. 2)l\ 



* I.e.^ the true period from ovulation followed by fertilisation (not from copulation) 

 to parturition. 



2 Naturalist^ March 1899, 7i- ^ Field^ 7th March 1874, 218. * Ibid. 



^ L. Jenyns, Observations on Natural History, etc. (London : Van Voorst), 1846, 56. 



* As by Carl Vogt, who examined twelve females, in five of which were two, and 

 in six only one embryo (see supra, p. 31). 



