BIRDS. 



48? 



(a, fig. 53) large spaces on the upper surface of the wings 

 are colored black, and include irregular white marks; and 

 from this state a complete gradation can be traced into a 

 tolerably perfect ocellus (a 1 ), and this results from the 

 contraction of the irregular blotches of color. In another 

 series of specimens a gradation can be followed from 

 excessively minute white dots, surrounded by a scarcely 

 visible black line (b), into perfectly symmetrical and large 



Fig. 53. Cyllo leda, Linn, from a drawing by Mr. Trimen, showing the extreme 

 range of variation in the ocelli. 



a. Specimen, from Mauritius, upper 



surface of fore wing. 

 a 1 . Specimen, from Natal, ditto. 



b. Specimen, from Java, upper sur- 

 face of hind wing. 

 ft 1 . Specimen, from Mauritius, ditto. 



ocelli (& 1 ).* In cases like these, the development of a 

 perfect ocellus does not require a long course of variation 

 and selection. 



With birds and many other animals it seems to follow 

 from the comparison of allied species that circular spots 

 are often generated by the breaking up and contraction of 

 stripes. In the Tragopan pheasant faint white lines in the 



* This wood-cut lias been engraved from a beautiful drawing, most 

 kindly made for me by Mr. Trimen; see also his description of the 

 wonderful amount of variation in the coloration and shape of the 

 wings of this butterfly, in his " Rhopalocera Africae Australis," p. 

 186. 



