340 BRITISH LEPIDOPTERA. 



S'25mm. long. September 9th, morning, 11 larvae hatched; afternoon, 4 larvae 

 hatched. September 12th, first larva showing traces of approaching ecdysis. Indica- 

 tions of shagreen-dots noticed in first and second larvae. September 13th, first larva 

 showing more distinct traces, and second larva showing traces of ecdysis (indications 

 of subdorsal line and green colour of blood noticed in first and second larvae). 

 September 14th, first larva 8-25mm. long when extended. Length of the 15 youngest 

 larvae from 7-75mm.-8 # 25mm. being almost at the close of the stage ; subdorsal can be 

 made out. September 1 7th, the first larva changed skin in morning, stage irrri i| days ; 

 the second in afternoon, stage 1— 10^ days. The youngest larvae have now been 

 preparing for ecdysis for some time ; very uniformly of a length of 8-25mm. when 

 extended. September 18th, 9.30 a.m., 8 had changed skin, stage 1=9 days. 10.30 

 a.m., 1 had changed skin, stage 1=9 days. 1.30 p.m., 2 had changed, stage 1=9^ days. 

 3.0 p.m., 1 had changed, stage 1=9 days. 10 p.m., 1 had changed, stage 1=9 

 days. September 19th, 9.25 a.m., 2 had changed, stage i=about 9^ days. 

 In the second stadium, the larvae show distinct traces of dimorphism, 

 and Poulton, for the purpose of description, grouped the 17 larvae that, 

 he reared into — ( 1) " pale " (ten), and (2) " dark " (seven), larvae. As in the 

 first stadium the Sphinx-like attitude was not observed, the larvae still 

 stretching themselves along the midrib on the undersides of the leaves, 

 but especially along the leafstalks and stems of the foodplant. When dis- 

 turbed, they were observed to wriggle from side to side and often to fall 

 from the foodplant ; they manifest very little disposition to wander, no 

 larva having been found off the foodplant in spite of continual disturb- 

 ance ; the larvae are fond of eating the leafstalks and stems as well as 

 the leaves of the foodplant. Towards the end of the second stad- 

 ium, as the skin becomes stretched, the larvae begin to assume a 

 somewhat glistening appearance. During the resting-period before 

 ecdysis the ground colour becomes lighter and of a more trans- 

 parent and yellowish green, the change being almost certainly 

 due to the comparative absence of food from the digestive tract 

 at this time. The average length of the 2nd stadium appears to 

 be about eight days, and the variations not more than one day on 

 each side of this. The larvae all entered the resting-stage preceding 

 the second moult on September 2 3rd-24th, and moulted between 

 September 24th (evening) and the 27th, a difference of nearly three 

 days between the earliest and latest in completing this ecdysis. 

 The larvae feed up rapidly in the 3rd stadium and after some six 

 days prepare for the third moult, those reared by Poulton entering 

 the resting-period between September 30th and October 4th, and 

 moulting between October 2nd and October 7th. During the 

 resting-period, individual larvae measured between 22mm. and 25mm. 

 in length. By this time, one larva had fallen behind the remainder 

 and Poulton states that there were indications that the slow growth of 

 this laggard was due to ill-health, for it was observed to have difficulty 

 in getting rid of its excreta during defecation, &c. (It did not 

 undergo its second moult till October 12th.) Poulton further 

 observes : " It is interesting to note that the larvae darken to a 

 considerable extent just before changing the skin, and certain 

 observations made at the beginning of the last stage render it pro- 

 bable that the air gains access to the new cuticle shortly before 

 ecdysis. The old cuticle is probably at this time dry, and not 

 sufficiently continuous or dense to exclude the presence of air. 

 Just previous to the 3rd moult, too, greater variation was observable 

 in the colour of the larvae, and Poulton reclassified the larvae as 

 (1) "lightest" (the six palest and bluest), (2) "intermediate" (four), 

 (3) " darkest " (the six darkest and yellowest), but after ecdysis many of 

 the palest larvae were quite dark. In the 4th stage, the larvae are 



