1873.] CHARACTERS IN THE CHIROPTERA. 249 



be found to possess structural differences depending on sex, as have 

 been described in other orders of Mammalia. 



It remains now to consider the secondary sexual differences arranged 

 under the second head — namely, differences in the colour of the fur. 



As the colour of the fur in Bats, as in other mammals, varies 

 very considerably according to age, season, and locality, it is neces- 

 sary in comparing males and females to pay particular attention to 

 this fact. Thus the common Flying Fox of Europeans in India, 

 Pteropus medius, Temm., varies considerably ; and the difference in 

 the colour of the fur of individuals obtained from different localities or 

 the same locality has caused some zoologists to rank them as distinct 

 species, though perfectly similar in structure *. There is probably 

 scarcely a single species of Bat to which this rule does not apply ; 

 but the variability of colour is often not noticeable in those in which 

 the fur is of a very dark shade. 



It is interesting to observe how Dr. Fitzinger, either from imper- 

 fect knowledge or from want of due appreciation of these facts, has 

 reproduced the mistakes of former observers by republishing the 

 names and descriptions of species previously recognized as synonyms 

 of other species, in some cases by the authors themselves. Thus 

 four species of Rhinolophus (Aquias) are recognized and described 

 (op. s. c. p. 192 et seq.) which differ from one another only in the 

 colour of the fur. And so we have, according to Dr. Fitzinger, " the 

 grizzled leaf-nosed Bat" (Aquias luctus, Temm.), "the reddish leaf- 

 nosed Bat" (A. eudouxii, Laplace), "the dark red leaf-nosed Bat" (A. 

 morio, Gray), and " the black leaf-nosed Bat " (A. perniger, Hodgs.). 

 Except the second named, these forms of R. luctus are in the Indian 

 Museum, and they have all been obtained at Darjeeling. Similarly 

 Kelaart's R. rubidus et fuhidus, which Blyth had shown to be 

 indentical with R. affinis, Horsf., are restored on the same grounds — 

 difference iu colour. 



The examination of many specimens of these Bats has shown me 

 that, where male and female specimens of the same species have 

 been obtained at the same time and place, the lighter-coloured speci- 

 mens are invariably males. This confirms Dr. J. A. Allen's obser- 

 vation regarding some species of American Batsf. Thus a male 

 specimen of R. luctus from Darjeeling, in the Indian Museum, 

 answers in every respect to the original description of R. morio, Gray ; 

 while several females from the same locality, and taken at the same 

 time, are wholly black, and belong, therefore, according to Fitzinger, 



* Dr. J. E. Gray notices tbe variability of colour in specimens of the same 

 species found in the same locality as follows : — " There is a general similarity in 

 the colouring of the majority of the species ; specimens found in the same 

 loca'ity or island often vary considerably from one another, even when the 

 examination of the skull and teeth show that they are of the same species. On 

 the other hand, specimens from different localities often resemble one another 

 so much in their external colouring that it is difficult to distinguish them in any 

 description that can be made ; but when the skulls and teeth are examined they 

 prove to be very different species." ("Revision of the Genera of Pteropine 

 Bats," Proc Zool. Soc. Lond. I8G6, p. 65.) 



t Quoted by Mr. Darwin, 'Descent of Man,' vol. ii. p. 286. 



