THE PUPA OR CHRYSALIS. 113 



entomological collection with a single chrysalis, or 

 aurelia, were, in fact, called " Aurelians." Reau- 

 mur explains that this golden appearance is caused 

 by the more solid texture of the chrysalis bein°- of 

 a rich yellow colour, and clothed with an external 

 and transparent membrane, beneath which is a 

 layer of fluid, which gives the metallic effect. If, 

 in fact, a newly formed cbrysalis of a Vanessa be 

 turned about, the gold patches will be found to 

 move with the fluid by which they are caused, and, 

 when old and dry, the golden hues disappear alto- 

 gether. The chrysalides of Moths are, as I have 

 said, almost invariably of various shades of brown, 

 from a light foxy tone to nearly black, but some 

 few are of more striking colours. That of Geo- 

 metra Alniaria, for example, is of a glaucous blue ; 

 that of Catocala Sponsa of a light lilac; that of 

 C. Facia of a delicate blue, arising from a kind of 

 bloom with which it is covered. This bloom is 

 easily brushed off, but reappears again in a short 

 time. 



Some few have the wing-cases of a different 

 colour to that of the shell; and the chrysalis of 

 Ti/grsra Anastomosis has two red stripes on the 

 back. 



The duration of the pupa stage is from a few 



I 



