HETEROGENEA CRUCTATA. 370 



dark brown in the male, yellow-brown in the female. Posterior wings 

 blackish. 



Variation. — Considerable sexual dimorphism is exhibited by this 

 species, the males being, usually, much smaller and darker than the 

 females, the fore-wings of the former varying from a colour which is 

 distinct purplish-black, through blackish-fuscous, to brownish-fus- 

 cous ; the palest specimens of this latter form are slightly tinged with 

 ochreous, and exhibit faint traces of a transverse oblique line rather 

 nearer the base than the centre of the wing, and an oblique shade 

 (rather than line) marking off the apical area. The darkest females 

 are brownish-fuscous, the paler forms vary through a dull (red-) brown 

 and yellowish-brown to a quite pale yellow colour. The principal 

 forms met with are : — 



1. — Blackish with purple tinge, <j = nigra, n. ab. 



2.— Blackish-fuscous, 3 = cruciata, Enoch, " alis nigro-fuscis " = asella, Fab. 



3. — Brownish-fuscous, somewhat mottled with dark ochreous, <? and ¥ = ab. 

 typica, n. ab., much the commonest form of the species in England. 



4. — Dull brown inclining to red-brown, ? — ab. intermedia, n. ab. 



5. — Ochreous-yellow, ? = &b.flavescens, n. ab. 



Ovum. — The mode of oviposition of this species was described 

 by Standish, who observed that some sarsenet with which he had 

 confined a female moth was bespattered with a whitish and glutinous- 

 looking substance, resembling gum or varnish. He concluded that 

 the substance was composed of eggs, although he could not detect an 

 egg of any shape. Buckler described eggs laid on" the side of a chip 

 box, on July 13th, 1877, as being agglomerated together, and being 

 " somewhat of a drop shape," but ill-defined, from their being con- 

 nected together in little lumps ; the colour, very pale, shining, trans- 

 parent and gelatinous-looking, otherwise much the colour of the chip ; 

 by the end of the month they began to grow yellowish, and then to 

 be tinged with the colour of brown sherry in parts of the little batches ; 

 after this, they began to hatch. Chapman states that the egg of this 

 species, like that of the last, is flat, ovoid, somewhat narrowed 

 towards one end, colourless, very transparent, with lozenge-shaped 

 network of cell-structure of the cell. The longest diameter is less 

 than '5 mm. 



Habits of larva. — The larva feeds on the edge of beech leaves, 

 and when eating the head ia withdrawn into the prothorax, which also 

 covers that portion of the edge of the leaf that is being devoured. 

 Probably the most peculiar point about it, is its mode of progression. 

 Buckler says that the six true legs are distinctly to be seen when the 

 larva is in motion, but no ventral or anal prolegs are perceptible, and, 

 instead of them, it has, along the margin of the venter, which is 

 deeply depressed centrally, a soft projecting ridge of extremely flexible 

 skin. This serves very well the purpose of legs, owing to its 

 undulatory movement from behind forwards; one wave at a time 

 being formed under each segment, and slowly advancing and sub- 

 siding in regular succession as far forwards as the first abdominal 

 segment. The larvse attach themselves so closely to the food-plant 

 that it is almost impossible to beat them. They must be searched for 

 in October on the beeches. 



Larva. — The newly -hatched larva, according to Buckler, is a mere 

 speck, of a rounded ovate figure, dark brown above and pale greenish 

 beneath, in short, a miniature representation, apparently, in all respects, 



