70 BRITISH LEPIDOPTERA. 



described in his account of the larva of T. porcellus as well as that of 

 E. elpenor (Studies in Theory of Descent, pp. 182, 187), that, when looked 

 at from the front, a larva in this attitude exhibits another pair of 

 ocellated marks, which appear as such in the defensive attitude only, 

 upon the 3rd thoracic segment. The "mirror" of this spot is formed 

 by the posterior end of the white subdorsal, the " ground-area " 

 by the black patch which encircles the former except anteriorly, 

 but there is no trace of a nucleus as in the spots on the 1st and 

 2nd abdominal segments . . . and Poulton points out that, 

 when the larva assumes the terrifying attitude and' the head 

 and thoracic segments are telescoped into the 1st abdominal, 

 the swollen anterior end of the body is abruptly truncated, and, 

 when looked at from the front, appears as a flattish circular face 

 marked by deep concentric furrows, which are the lines between 

 the segments and between the annuli which are upon the latter. 

 The result of these deep furrows, and of the shortening of the 

 subdorsal is to render the latter, and its deep margins, inconspicuous, 

 except in the posterior part of their length, where they become 

 broadened, shortened, and rendered very prominent, as two eye- 

 like marks, one on each side of the median line and towards the 

 upper margin of the face-like extremity of the larva. Their position 

 is, therefore, exactly that which, better than any other, produces 

 the effect of eyes upon an enemy approaching from the front. 

 Although the white "mirror" is not completely encircled by the 

 ground-area, no impression of imperfection is produced and the 

 effect of the furrows and contraction is such as not to suggest 

 the continuity of the eye-like parts of the subdorsal and its 

 margins with the rest of these markings on the anterior thoracic 

 segments. These two eye-like marks differ from the others in 

 that they only possess significance in the terrifying attitude, 

 being quite unrecognisable as eyes in any other position. This 

 must certainly add to the effect of the suddenly assumed protective 

 attitude, when, in addition to the changed contour of the larva 

 and the prominence given to the large eye-spots, with equal sudden- 

 ness new terrifying marks seem, as it were, to spring into existence. 

 Larva. — First instar (newly-hatched) : The newly-hatched larva 

 of E. elpenor has the head and body yellow-green in colour, the 

 legs and prolegs paler and almost transparent ; the caudal horn 

 long in proportion to the length of the larva, black in colour, and 

 slightly bifid at tip ( Ent. Eec., ix., p. 237). Length on hatching 

 i'5rara., pale green in colour, changing after a few hours to dark 

 grey; segmental incisions appear as white rings, due to over- 

 lapping of skin. Head rounded, pale green, with a few small 

 scattered hairs thereon ; slightly wider than prothorax, but not 

 large for size of larva. Prothoracic scutellum large, but not 

 distinct, more opaque in colour than the head. Tubercles i and 

 ii on meso- and metathorax placed trapezoidally on separate sub- 

 segments, iii is double on these segments, and only one subspiracular 

 hair (v) is traceable ; i and ii on abdominal segments in the usual 

 trapezoidal form, the anteriors (i) on the Sth abdominal segment 

 being on the summit of caudal horn ; iii is a single-haired tubercle, iv 

 is single-haired below spiracle ; each of the tubercles bears a single, 

 very short, light-coloured seta, slightly knobbed at tip. The caudal 



