370 BRITISH LEPIDOPTERA. 



greyer in tone, with the transverse lines strongly marked, and the hind- 

 wings dark grey. A few specimens have the transverse lines almost 

 obsolete, whilst others are very small, and are much below the average 

 size of normal individuals of this species. The principal forms are: — 



1.— Orange- or red-brown, much suffused with black, <? = asella, Esp., 

 Die Schmett., p. 36, " alis fuseis." 



2.— Orange- or red-brown, with distinct, blackish, transverse band, <? = 

 ab. bitfo, Fab., Mant., no. 118, p. 121, "fascia lata fusca." 



3. — Orange- or red-brown with transverse lines, 3 = avellana, Linn. 

 This appears to be the male form corresponding with the female form described 

 by Linne. 



4. — Yellow-ochreous inclining to orange, with transverse lines and yellowish 

 hind-wings, ? = ab. sulphurea, Fab., Gen. Ins., " alis fiavissimis : strigis duabus 

 obliquis obscurioribus." 



5.— Yellow-ochreous with distinct transverse lines and greyish hind-wings, 

 ? = ab. testudo, Fab., " alis flavis, strigis duabus obliquis obscurioribus." 



6. — Ochreous tending to testaceous, strongly marked transverse lines, grey 

 hind-wings, ? = avellana, Linn. 



7. — Two-thirds or less the size of normal specimens, in expanse of wing = ab. 

 minor, n. ab. 



8. — Dark brown, with two transverse lines and with yellow blotches (one on 

 inner margin between the lines, and another on the outer line), <? = ab. Umax, Bork. 



Ovum. — The egg is 1*06 mm. in length, and *75 mm. in width, flat, 

 oval, colourless and transparent, with a lozenge-shaped reticulation 

 covering the shell. The reticulation can be easily seen if examined in 

 a suitable light, with a moderate magnifying power. The egg also 

 lends itself readily to observation under a microscope, owing to 

 its transparency, flatness, and the facility with which the moth can 

 be induced to lay its eggs on glass. Burrows says that the eggs are 

 laid naturally at the angles of the veins on the back of an oak-leaf. 

 They are yellowish at first, then become grey, and hatch within ten 

 days. Horton notes that a female lays more than two hundred eggs ; 

 he gives the egg as above one-twentieth of an inch in diameter, very 

 large for the size of the moth, colour pale yellow, with an opaline 

 appearance. 



Habits of larva. — The larva rests on the upper surface of the 

 leaves of its food-plant. The body is inflated so that a somewhat 

 dome-like shape is produced, depressed slightly, however, at the sides. 

 The larva is not, at first sight, much unlike some Lycrenid butterfly 

 caterpillars, and has a peculiar undulatory motion, due to the absence 

 of prolegs, which has earned for the insects the name Cochliopodids 

 ("slug-footed"). Poulton believes that, at first, larvas of this kind 

 walked by means of adhesive claspers, and that these gradually 

 became shorter and broader, thus giving increased support by extending 

 the area by means of which they adhered ; gradually, he considers, the 

 prolegs were lost, and the whole of the ventral surface took part in 

 locomotion. As a matter of fact, the ventral surface is now covered with 

 adhesive matter, and the larva leaves a silken band when it walks on 

 glass ; this band becomes white and opaque, and does not much resemble 

 ordinary silk. Even when the larva is mature, and coiled up in its 

 cocoon during the winter, previous to pupation, the ventral surface is 

 covered with an adhesive material, so that, on touching this surface 

 with a knife or other smooth object, the larva may be raised from the 

 cocoon, the adhesive matter being quite sufficient to bear the weight of 

 the larva. The suckers, which replace the abdominal prolegs, also aid 

 greatly in progression, 



