60 THE BOOK OF BRITISH BUTTERFLIES. 



The chrysalis is of the singular shape shown in 

 Fig. 43, somewhat resembling a half-moon, the two ex- 

 tremities being very 'much pointed. It is dull green 

 dorsally and brownish-pink ventrally. The wing-cases 

 prpject on the ventral surface as a kind of arch, while the 

 dorsal surface is concave. 



There is a somewhat close similarity between P. daplidice 

 and the female of A. cardamines (though the differ- 

 ence is considerable when the butterflies are compared), 

 consequently when identifying either, especially from 

 a description,* great care must be used. The ground- 

 colour of the imago (Figs. 44 to 47) is white, all the wings 

 are rounded, and the costal margin is slightly convex. 

 On the upper surface at the tip of the fore-wings 

 is a greyish mark extending about two-thirds down 

 the hind-margin, while on the margin itself there 

 are little patches of white between the nervures, which 

 on the hind-wings are tipped with black. There is a 

 semicircular black patch in the middle of the fore-wings, 

 usually smaller in the male, as also is the patch at the 

 tip ; the base of the wings is clouded with black. The 

 central spot is smaller than in Pieris daplidice, and not 

 divided by a white streak as in the latter. On the under- 

 surface (Figs. 45 and 46) the grey tip of the fore-wings is 

 replaced by faint greenish markings on the nervures, and 

 the central spot is repeated. The hind-wings are beauti- 

 fully chequered with well-defined green markings on a 

 white ground. (In P. daplidice the green markings are 

 toned down.) The bright orange patch covering the hind 

 half of the upper surface of the fore-wings, and repeated 

 in part below, distinguishes the sexes. It should be 

 noted that as in P. napi the green markings are pro- 

 duced by a mixture of black and yellow scales, easily 

 separable under the microscope. 



