102 BRITISH LEP1DOPTERA. 



instar: The blue-green coloration remains unchanged, but a some- 

 what darker green dorsal line becomes apparent down the middle 

 of the back (the dorsal vessel?), and the subdorsal line now 

 becomes very broad and pure white, being much more conspicuous 

 than in any stage of E. elpenor (fig. 25). The tapering of the 

 three front segments occurs at this stage, and oblique dark green 

 striations on a lighter ground stand out distinctly on the spiracles. 

 As with E. elpenor, the first traces of the future eye-spots appear 

 during the 2nd stage, not in the present case as a curvature of 

 the subdorsal line, but as a spot-like widening of the latter, of a 

 brighter white than the somewhat greenish colour of the remainder 

 of the line. Third instar : After the second moult, the formation 

 of the dark "ground area" (anted, p. 76) of the eye-spots com- 

 mences by the appearance of a little brown on the under edge 

 of the foremost of the white spots, this coloration gradually in- 

 creasing in extent and in depth. At the same time both spots 

 become more strongly distinguishable from the subdorsal line, which 

 becomes constantly greener (fig. 27). The brown colour soon 

 passes round the white of the front eye-spot, which becomes so 

 far perfected, whilst the completion of the hind spot is effected 

 slowly afterwards. The formation of the eye-spots does not, there- 

 tore, proceed any more rapidly in this species than in E. elpenor. 

 At the end of the present stage, the larva is about 4cm. in length ; 

 the ground-colour is still . sea-green ; the subdorsal line is much 

 diminished, completely fading away at its lower edge, but remaining 

 sharply defined above against the green ground-colour (fig. 26;. 

 Fourth instar : After the 3rd moult all the larvae (5) became 

 brown, this change occurring, therefore, one stage earlier than is 

 generally the case with E. elpenor* \ In single instances, the brown 

 colour appeared in the 3rd stage. The subdorsal line had dis- 

 appeared from all the segments but the first three and the last. 

 The eye-spots now rapidly attained complete development ; they 

 contained a black pupil, and gave the insect a truly repulsive 

 appearance when, on being threatened by danger, it drew in the 

 front segments and expanded the 4th (fig. 28). The eye-spots of 

 the 5th segment are much less developed than in E. elpenor • 

 they remain small and are not readily detected. On the 

 other hand, there now appear on all the segments, with 

 the exception of the last, just as in the 6th stage of E. 

 elpenor, distinct rudiments of eye-spots, which present the ap- 

 pearance of irregular, roundish, black spots on the front 

 borders of the segments, at the height of the former subdorsal 

 line. In this latter region, the black pigment is disposed as a 

 longitudinal streak, and, to this, a median line is added, the whole 

 forming a marking which, perhaps, makes the caterpillar appear 

 still more alarming to its foes. This marking is, however, only 

 to be distinctly recognised on the first three segments. The 



* This wants carefully comparing with our account of the larva of E. elpenor 



(antra, p. 72), in which il is shown that blown forms oi the larva of E. elpenor 

 appear in the 4th stadium, as in that of V. porcellus. We have already hinted 

 [anted/., p. ~(>) that Weismann stands alone in allowing six larval stadia to E. elpenor. 

 Also comparewith our description oi larva of J\ porcellus (antea, pp. 100-101), where 

 it is noted that many larvae OI T. porcellus do not become dark till the last instar. 



