THE GREATER HORSESHOE BAT 231 



is one of the most striking facts in the distribution of British 

 mammals. 



Distritoution in time :— Bones of this bat from Kent's Hole, near 

 Torquay, appear to be of very different ages, some resembling in con- 

 dition those of mammoth, hycnena, and rhinoceros found with them, 

 while others are quite recent (see Owen, British Fossil Mammals, 

 etc., 15-16). 



Breeding season, and number of yoimg: — Very little information 

 on these points has been published by British naturalists. In Germany 

 the young are stated to be two, sometimes only one (Kuhl), but Rollinat 

 and Trouessart, whose interesting observations {Coviptes rendus Soc. 

 Biol. (Paris), 26th January 1895, 53-54. and 6th July 1895, 534-536; also 

 Mem. Soc. Zool. de France, x., 1897, ^ 4-134) have been strangely over- 

 looked, find that in France the latter number is never exceeded. 



As in the Vespertilionidcz, copulation takes place in the autumn (but 

 see under R. hipposideros), the earliest date at which spermatozoa have 

 been found in the uterus of a female being 5th October. After copula- 

 tion the spermatozoa become imbedded in a " bouchon " or body formed 

 of mucus hardened after secretion within the vagina. In October the 

 females are extremely fat, the mammary glands show no trace of milk, 

 the ovaries are small and pale rose-coloured, the uterus normal with the 

 exception of a slight enlargement of the right horn, but the vagina full 

 of a thick white substance, rich in spermatozoa. By November this has 

 hardened to form the " bouchon." 



Ovulation and fertilisation take place in March, or more often, 

 early in April {DxivdA, Jonru. de rAnat. et de la Physiol., xxxi., March- 

 April 1895, 93-160), the exact date depending on the conclusion of the 

 hibernatory sleep. A female kept alive by Coward for nine weeks was 

 found to contain a small embryo on 28th February, but hibernation had 

 been interrupted during the whole period of captivity. 



The fertilised ovum invariably takes up its position in the right 

 horn of the uterus. Subsequently the " bouchon," now of no further 

 use, is expelled from the vagina, tearing the vulva in its passage. 



By the end of April the right horn of the uterus containing the 

 embryo is as large as a pea or a very small hazel nut, and the first 

 young one was observed clinging to its mother on the 20th June. 

 The period of gestation is, therefore, ten to twelve weeks. By 3rd 

 July most of the young are born, but late births take place up to 

 about the 20th ; the mothers have the pectoral mammary glands fully 

 developed, but the nipples are shorter than the false ones of the pubis : 

 the uterus is in atrophy, but the right horn still forms a large pocket. 



Young of the first year, of both sexes, although associating with the 

 breeding females, prove on dissection to be not sufficiently developed to 

 breed ; the young females pair in their second autumn ; the internal 



