DED UCTION. ANTIC IP A TION. I 5 5 



the most rigorous test. The ocelli on the tail 

 of the peacock furnished such an instance. The 

 problem was how to explain the origin of these 

 ocelli from the ordinary feather markings of 

 the group to which the peacock belongs. 



First, his belief that the colotf patterns of 

 many birds are due to sexual selection led him 

 to explain the absence of ocelli from the tail- 

 feathers of the two species of peacock by the 

 fact that these feathers are covered up and con- 

 cealed by the long tail-coverts. The theory 

 required that the patterns due to sexual selec- 

 tion should be exposed to the gaze of the 

 females. "In this respect," he said, "they 

 differ remarkably from the tail-feathers of Poly- 

 plectron, which in most of the species are orna- 

 mented with larger ocelli than those on the 

 tail-coverts." According to theory, the ocelli 

 had disappeared from the tail-feathers and 

 been remarkably developed on the tail-coverts 

 because the latter by enormous development 

 had covered the former. In Polyplectron, in 

 which the tail-coverts are not so enormously 

 developed, the ocelli were larger on the tail- 

 feathers than on the coverts. By the theory, 

 however, the markings of the Polyplectron are 

 more generalized, and some indications of 

 gradations between these two extremes ought 



