262 ANIMAL COLOEATION. 



of pairing. The mane of the lion and the beard of man belong 

 to the same series. Sexual diiferences in colour among the 

 Mammalia are not common ; the most striking instance, per- 

 haps, is one referred to by Mr. Wallace * — Lemur macaco ; 

 the male of this lemur is black, and the female bi'own. 

 Dr. Dobson f has brought together some interesting examples 

 of sexual dimorphism among bats. There are, in addition to 

 various remarkable structural differences between the two 

 sexes, occasionally colour diiferences. These colour diiferences 

 are frequently developed only at the breeding season. In a 

 common Calcutta bat, Nycticeius temmincki, the under parts 

 are usually of a pale straw colour ; but in females captured 

 during the months of March and April the prevailing hues 

 were a rich saffron. It is important to notice, however, from 

 the point of view of sexual selection, that colour differences 

 are more common among the frugivorous bats, and they have 

 a better sense of sight. 



Dependence of Sexual Dimorphism upon the Generative Organs. 



The dependence of colour and other secondary sexual 

 characters upon the essential organs of reproduction is almost 

 too well known to need illustrating by examples. I shall, 

 however, refer to two recent instances which have been 

 carefully described. Prof. Max Weber of Amsterdam % has 

 examined a chaffinch, in which the left side of the body has 

 the coloration of a hen bird, the right that of a cock, which 

 are sharply marked off from each other in the middle line. 

 An examination of the viscera showed that the bird was a 

 hermaphrodite, with a well-developed ovary on that side of the 

 body which was clad with the plumage of the female, and a 



* " Darwinism,'' p. 282. 



t Proc. Zool. Soc, 1873, p. 241. 



t Zool. Anzelger, 1890, p. 508. 



