228 BRITISH BUTTERFLIES. 



also is the form, with ridges, and points left by their intersections, 

 than with the Lycaenid form of egg, of a network, with knobs at the 

 intersections ; there are, indeed, no indications of knobs. Apart from 

 the surface sculpture, the eggs proper of Bitliys quercus, Ruralis betulae, 

 Strymon pruni, and Edwardsia w-albuni, are probably all much the 

 same, but the sculpture makes them differ much in external appear- 

 ance, due to the different form and development of the adventitious 

 coat, which is the feature of nearly all Lycasnid eggs. ■ The egg of 

 Ruralis betulae is (of these four) at one end of the series, having a very 

 thick coating, in which the cells, especially in the upper part of the 

 egg, are reduced to mere slender tubes by the great thickness and 

 coalescence of the columns and connecting ribs. At the other 

 extremity is Edwardsia w-album, in which the coating is fairly 

 developed marginally, but over the dome of the egg is reduced to a few 

 hairs, the representatives of the columns, the eggshell proper being 

 very fully exposed. The apparent shape of these two eggs is, 

 therefore, very different, that of R. betulae being high and rounded, 

 that of E. tv -album flat, and with a flange-like margin. The egg of 

 R. betulae is also snowy white, the coating only being visible, E. 

 w-album takes a dark colour from the true egg, and its contents being 

 evident. The eggs of Strymon pruni and Bithys quercus are very much 

 alike in having a moderate and fairly developed coating of very similar 

 pattern. I have never seen these just laid, but fancy they are even 

 then dark, as compared with that of R. betulae. 



The Euraline larva shows considerable difference from the Strymonid ; 

 the latter is characterised by the depression of the prothoracic plate, the 

 great hood formed by the mesothorax, the wide depression formed between 

 the double dorsal ridge and waved slopes, whilst, in the former, the 

 mesotborax is comparatively flat, the sloping sides very straight, the two 

 dorsal ridges approximating, and quite flattened at the apex, and not 

 presenting at all the humped outline, as observed in Strymon (pruni), 

 Edwardsia (ir-album), etc. Chapman says : The newly-hatched larvae 

 of Ruralis betulae and Bitliys quercus agree in having abundant hairs 

 and lenticles on the prothoracic plate, that of Edivardsia w-album has 

 comparatively few, and on that of Strymon pruni there are six hairs, 

 but no large lenticles. In R. betulae and B. quercus, the great lenticle 

 on the slope has two small associated hairs. In S. pruni, it is 

 accompanied by a small lenticle, which, in E. w-album, only occurs on 

 the 1st abdominal segment, on the following segments it is solitary. 

 In R. betulae and B. quercus, there is also, on the 1st and 2nd 

 abdominal segments, a large lenticle, near spiracle in the same group, 

 just above spiracle, however, in B. quercus, below and in front of it in 

 11. betulae, a very material difference, therefore, between these two 

 species. All four species have tw r o pads with hooks, in common with 

 so many Lycsenids, on each proleg; each pad carries two, rather large, 

 hooks, and there is the central fleshy process. In B. quercus, however, there 

 is, on the outer margin of the base of the pads, a little row of four or 

 five very small hooks, of which no trace exists in S. pruni or E. w-album. 

 In R. betulae, this row is even more developed than in B. quercus, and 

 some nine or ten hooks exist in it. There are some other minor 

 differences in the distribution of the lenticles, but in more important 

 features, the only notable difference is the absence in N. pruni of the 

 small hair in front of tubercles i and ii. The larvae of the species of 



