1873.] MR. G. E. DOBSON ON THE CH1ROPTERA. 241 



5. On Secondary Sexual Characters in the Chiroptera. 

 By G. E. Dobson, B.A., M.B. 



[Received February 11, 1873.] 



In the first volume of ' The Descent of Man ' (p. 268) Mr. Darwin 

 writes as follows : — " Hardly a single species amongst the Chiroptera 

 and Edentata, or in the great orders of the Rodents and Insectivora, 

 presents well-developed secondary sexual differences " 



I purpose in this paper to inquire into the applicability of 

 Mr. Darwin's statement so far as regards the first of the orders 

 referred to, the Chiroptera ; and I hope to be able to show that 

 several species in this order present well-marked secondary sexual 

 differences. 



As in other orders of Mammalia these differences may be con- 

 sidered under two heads : — 



J . Differences in structure. 



2. Differences in the colour of the fur. 



The first is the most important and constant character ; the 

 second is observable in by far the larger number of species possess- 

 ing secondary sexual characters ;. but the distinction between male 

 and female in this respect is less well-marked generally in the Chiro- 

 ptera than in some other orders of Mammalia. 



I shall therefore first enumerate and describe the secondary 

 sexual characters depending on structural differences which have 

 been observed in the Bats of the eastern hemisphere. 



Among the Rhinolophidce, or Horseshoe Bats, the species of the 

 genus Phyllorhina present most remarkable secondary sexual 

 characters. The males of sixteen species are provided with a 

 peculiar frontal sac, placed immediately behind the erect portion of 

 the transverse nose-leaf. The sides of this sac are usually covered 

 with a peculiar waxy secretion ; and a pencil of long, fine, black 

 hairs arising from the bottom of the sac projects for about half its 

 length from its mouth. " This cavity," remarks Mr. Elliot (quoted 

 by Blyth *), " the animal can turn out at pleasure, like the finger 

 of a glove ; it is lined with a pencil of stiff hairs, and secretes a 

 yellow substance like wax. When alarmed, the animal opens this 

 cavity and blows it out, during which it is protruded and withdrawn 

 at each breathing." In the females this frontal sac is quite rudi- 

 mentary, consisting only of a slight depression in the skin of the 

 forehead surrounded by a cutaneous ring. From the bottom of this 

 depression hairs project, as in the males, but are much finer and 

 shorter. 



In every known species of Phyllorhina a small, wart-like glandular 

 elevation, covered with fine straight hairs, and having on its summit 

 two small apertures, exists on either side of the forehead behind the 

 transverse nose-leaf, slightly internal to and above the eye. Between 

 these glandular prominences the frontal sac is placed in all species so 

 provided. In the adult males of P. armigera, Hodgs., the wart- 

 * Journ. .Asiatic Soc. of Bengal, vol. xiii. p. 487. 



Proc. Zool. Soc— 1873, No. XVI. 16 



