THE HEATH FRITILLARY. 99 



There is a good deal of variation on the under side, but chiefly 

 of a minor character, and most often unconnected with variation 

 on the upper side. The following are more important varieties. 



Var. tessellata, the Straw May Fritillary of Petiver, and figured 

 by him in 1717 and by Stephens in 1827, has the under side of 

 the hind wings entirely straw-coloured with black veins. There 

 are three large squarish yellow spots on the basal area, outlined 

 in black ; a yellow central band, margined and traversed by 

 black lines. On the outer margin there is a series of yellow 

 crescents, outlined in black. 



Var. eos of Haworth (the Dark Under-wing Fritillary) is the 

 pyronia of Hiibner and Stephens, and a modification of var. 

 coryt/ialza y H\ibn. On the under side the fore wings are fulvous, 

 and have two black spots in the discal cell, and a black band, 

 intersected by the veins, on the central area. On the hind wings 

 the basal third is fulvous with eight black spots ; the central area 

 is whitish intersected by the black veins. On the yellow-tinged 

 whitish outer area there is a series of black-margined orange 

 crescents ; a row of black lunules precedes a thin black line on 

 the outer margin. 



The egg is upright, ribbed, and pale whitish-green in colour. 

 As the caterpillar matures the shell becomes greyish. The eggs 

 were laid in a cluster on a leaf of cow-wheat (Melampyrum 

 pratense) as shown in the figure, but failed to hatch. 



The full-grown caterpillar is black on the back, becoming 

 olive tinged on the sides and olive-brown underneath ; the 

 divisions between the rings are olive. The whole of the upper 

 surface, except a line along the middle of the back, is dotted 

 with white, and there are eleven white-tipped orange *or 

 yellowish spines on each ring, except the last two and the 

 three nearest the head ; the first and the last each have four 

 spines, the third has eight, and the second and the eleventh 

 have each ten spines. The head is black marked with white, 

 and is clothed with short, stiff, black hair or bristles (Buckler). 



