5G r August, 



as the larva-skin has cleared the wings of the chrysalis, I secure the 

 latter in its position by two small pins in the groove between two of 

 the abdominal segments, and then draw down the skin gently over the 

 tail and pin it to the side of the cork. If too much traction has not 

 been used, and if the operation is not too long delayed, I find that the 

 everted skin is held back at the anal horns, and also pei-haps laterally 

 at the last two spiracles. The latter adhesion soon gives way ; and, 

 as the drawing efforts of the chrysalis go on, or if further traction is 

 made on the larva-skin, the outer coat of it will be seen to part freely 

 from the transparent inner coat, and be drawn out from between the 

 two folds of the latter, which by degrees coalesce and assume the form 

 of the ligament. This inner coat of the caterpillar-skin is elastic, 

 very distensible, and of a semi-plastic consistence, and readily runs 

 into the ligamentary form under the influence of tension alone. 



Of course the eversion and retraction of the larva- skin is an arti- 

 ficial interference, without which it may be doubted whether the 

 separation of the coats woidd take place. Certainly, the greater the 

 traction the more of the lining coat will be drawn out, and the longer 

 will be the resulting ligament ; but the artificial traction does not act 

 more on the one coat than the other with the tendency to separate 

 them. Eather, in the natural circumstances, where the weight of the 

 pupa is exercising tension on the inner coat alone, while the upward 

 thrust of the insect is acting chiefly on the outer, would the conditions 

 be favourable to the separation of the coats, and the drawing out of 

 the inner one into a ligament. At all events, there seems to have 

 been no artificial traction used in the cases described by Mr. Edwards ; 

 and, at all events, this adhesion of the lining membrane of the cater- 

 pillar skin to the anterior horns of the anal ridges, remains as the 

 efficient cause of the suspension of the chrysalis while its tail is being 

 removed from the old skin and till its hooks are fastened in the silk. 



In urticie the two crescentic whitish ridges embracing the anal 

 area terminate anteriorly in horns, which project over the segments 

 immediately in front. These horns have on the inner side a black 

 knob, terminating a black line, which runs along the under inner side 

 of each ridge, separated from the rest of the horn (the outer whitish 

 knob) by what seems a small groove. Now, it is finally to these black 

 knobs alone that the ligament is attached, and when the tension is 

 great and prolonged, the corners of the ligament are pouched out by 

 them into hooks or shallow pockets. But the adhesion of the pupa to 

 the ligament is not a merely mechanical one (as if it were only slung 

 by the insertion of tliese projecting knobs in the pouches of the 



