242 BRITISH LEPIDOPTERA. 



batches. The eggs laid by the second $ between March 25th and 27th 

 commenced to hatch April 23rd, and continued to do so until after 

 April 28th. Jones found at Rannoch in May, 1883, n ova laid in a 

 row, side by side and touching, on a small twig of birch ; these hatched 

 June 1 st, all the larvae coming out of the same end of the eggs, and 

 each making a circular hole in it. Wynn discovered eggs in 1891 

 in Wyre Forest laid in little clusters, at the end of thin twigs of 

 birch. Day found eggs at Rannoch at the end of May, 1898, 

 laid scattered on twigs of alder. Buckler notes that a small 

 batch of a dozen eggs from Rannoch began to hatch May 22nd, the 

 larvae continuing to appear at intervals throughout that day, and up to 

 the next morning when the two latest were hatched. Jenvey writes 

 (/./.) that two batches (laid by ? s, which were both fertilised by the 

 same male) consisted of 126 and 138 eggs respectively, and were 

 deposited on birch twigs. Holland records eggs as being found wild 

 at Burghfield on a birch bush on May 13th, 1891. 



Ovum. — When first laid yellow, soon assuming a dirty tint, the 

 colour getting deeper, till it is of a deep purple or red-brown hue 

 with a strong tinge of bluish. Before hatching, air penetrates between 

 the larva and the shell, the colour being then a dirty white, i.e., 

 a white semi transparent shell over a black (brown-haired) larva. 

 The eggs are plump and round when laid, but soon, by desiccation, 

 develop a deep dent on one side, and this may assume really large pro- 

 portions without detriment to the final exclusion of a healthy larva. 

 The egg is nearly cylindrical with hemispherical ends ; it does, how- 

 ever, deviate a little from a strictly cylindrical form. The length is barely 

 2-omm., and the greatest diameter, i-^mm., the least being roomm. 

 This is the extent of the flattening in a plump egg, but the flattening 

 from shrinkage soon makes this flattening much more pronounced. 

 The micropyle is represented by a minute cell surrounded by a 

 rosette of eight rather elongated cells, the whole rosette being about 

 0-03111111. across, and, outside this, is an area about 0*5111111. in 

 diameter, with a well-marked network of cells, apparently separated 

 by slightly raised lines ; these cells are of very irregular form, 

 usually lengthened in a direction radial from the micropyle, 

 often four-sided, twice as long as broad, and about 0-025111111. 

 in length, but longer as they recede from the micropyle ; outside 

 this area they become less distinct, but can often be made out, although 

 they usually present the appearance of a minutely undulated surface. 

 There is another appearance that is very marked, but of the exact 

 nature of which it is more difficult to be sure. This may be described 

 as beginning outside a radius of -25111111. from the micropyle, and 

 affecting more or less the rest of the egg, and presenting the 

 appearance of a number of fine spicular hairs arising at a con- 

 siderable number of the points of intersection of the mesh of 

 network. These are very fine and have a silvery sheen. Sometimes 

 they appear to rise from a globular base. In some aspects, however, 

 they look like small raised splashes, or marks of exclamation, laid 

 flatly on the egg surface, with a minute free point standing off. 

 They probably are portions of the network specially developed, and are 

 not free spicules, except perchance at their extreme ends. The egg-shell 

 being almost transparent, and being on a dark ground, its inequalities 

 and markings probably produce these puzzling effects in various lights 



