RUEALIS BETULiE. 285 



zigzag wall between two rows of pits. It forms an extremely curious 

 and beautiful object, though to say more so than many others of these 

 Lycasnid eggs, might be going too far, though one inclines to make 

 the assertion with regard to each one of such eggs that one happens 

 to be examining. The examination of this egg demonstrates that the 

 elaborate sculpture of these Lycaenid eggs is in a superadded layer, 

 distinct from the true eggshell ; at some points one looks down the 

 tubes or pits and sees them apparently widening out again below, and 

 leaving nearly bare portions of the true shell (February, 1906). This 

 egg is roughly a white ball. The superficial corky layer enveloping 

 the Lyca3nid egg is in it especially developed as a white snowy layer, or 

 rather, perhaps, as a sugar-icing. Assuming the typical form of this 

 layer to be a more or less hexagonal network, of which the lines of 

 reticulation are built up to a great height so as to form a honey- 

 comb structure, in R. betulae the walls are so thickened that the cells 

 of the comb are mere circular pits round the shoulder of the egg, about 

 one-quarter or one-third the thickness of the walls in diameter, and round 

 the micropylar area they are not much more than indicated. In this 

 situation some eggs show a smooth surface with a few minute holes ; 

 in these the funnel-like widening of the top of the cell, which is 

 marked elsewhere, obtains here also, and the walls form wide rounded 

 ridges, about thirteen in number, more or less radiating from the 

 centre, owing to the funnels of the cell, in lines of radiation, inter- 

 secting more freely than in other directions. The intersection of 

 the funnels makes angular points project at the angular point of the 

 network (or honeycomb), which are sharp about the shoulder or mid- 

 zone of the egg, but lower down are more rounded, and more definitely 

 project beyond the mere intersection of the funnel, and are, therefore, 

 more spinous in character, though with blunter tips. The micropylar 

 area is at the bottom of a very deep, central, circular pit, some 012rnm. 

 across. At the bottom of this is seen a star of six cells ; each pear- 

 shaped, with the point central, and especially remarkable in their 

 outlines, being brilliantly white and the rest of the surface greyish, and 

 the corky substance apparently dense enough to obscure any cells 

 outside the star, which, therefore, stands out more brightly than in 

 any other egg (at any rate of any one recently examined), and makes 

 it very obvious though at the bottom of the pit, and obviates the 

 necessity of getting a piece of an empty shell to observe it. The 

 actual diameter of the micropylar rosette is 0-044mm. The depth of 

 the micropylar pit is considerable, but not easy to measure. The egg is 

 about 0'75mm. wide and 045mm. high, but the true egg, were the 

 white coating absent, must be much less than this. The pitting (or 

 honeycombing) round the slope of the egg is strictly hexagonal, about 

 O06mm. from centre to centre. The lines of the cells are (1) circum- 

 ferential and (2) oblique. They appear to be continued beneath the 

 egg (Chapman, November 20th, 1906). Colour pure white. The 

 egg rises in the shape of a depressed sphere to about five-sixths of 

 its entire height, above which it is continued in the form of a cap. 

 Under the lens the egg is seen to be beautifully and perfectly ribbed with 

 minute ridges, which divide it into hexagonal cells, giving it a honey- 

 comb appearance. The array of these cells is very conspicuous when 

 viewed sideways. Before reaching the cap-like top, the cells gradually 

 increase in size. At the topmost point there is a comparatively deep 



