254 LApril, 



Tlie jjemdiimate moult occurred on 13th May, and gave the extra length to the 

 first pair of spines behind the head, with their blunt tips black ; all the other spines 

 amber-jcllow ; on the same day, only three hours later, another individual was well 

 over the corresponding moult, and to this one also I devoted especial notice ; of the 

 remaining two larvse still kept together, it will be enough to say here that they 

 showed the extra length of the front spines on the loth and 16th of May ; the 

 growth of all continued, and in seven days the first, specially noted above, was a 

 little over an inch in length, and the second about an inch ; neither appeared up to 

 this time to feed very often, but each made a good meal twice a day. 



I observed the first larva, in preparation for its last moult, fixed, belly upward, 

 to the under-side of a leaf, on 20th of May, and remaining quite still until noon of 

 the 25th, when I noticed it moving its anterior legs a little free from the leaf, a cir- 

 cumstance which claimed my whole attention : it was but a slight movement, and 

 was repeated at intervals of about half-an-hour, until between two and three o'clock 

 in the afternoon, when it began to stretcli its front segments downwards from the 

 leaf, making the fore part of the back concave, and then presently gently reversing 

 the movetnent ; it continued thus at short intervals to increase the stretching curve 

 of the body so much, that, by ten minutes past three, its hold on the leaf was re- 

 tained only by the fourth pair of ventral legs and the anal pair, when suddenly the 

 skin snapped asunder, close to the head, with quite a shock to the larva, which 

 instantly returned its ventral legs to the leaf, while the elastic skin, relieved of its 

 tension, was, of itself, from the impetus of the rupture, gliding backward ; the 

 anterior legs were held back until divested, and then returned forwards to their 

 natural position one after the other, but kept just free from the leaf, each pair being 

 elevated in unison for a moment, and let fall, as though to test their complete free- 

 dom ; otherwise the larva remained passive, the skin only continuing to move 

 backward, and, while passing the ventral legs, each foot in tm-n was lifted up out of 

 it, and then replaced on the same spot of the leaf, and when the old skin had 

 shrivelled up together at the end of the body, the larva, with all the ventral legs, 

 took two steps forward, and drew forth the anal pair free ; at the first breaking of 

 the skin the head became exposed, with the old head-piece adhering to the parts 

 around the mouth, but now, at last, the larva gave its head a sudden twist or two, 

 and the old piece fell off : from the rupture of skin to this final riddance, the 

 operation occupied nearly ten minutes ; the spines were all uncovered in a remark- 

 ably small and rudimentary, wet, and flaccid condition, tlio front pair even smaller 

 than the others j but now this pair began gi-adually to grow, and in fifteen minutes 

 were far longer than ever, and in another half-hour all the other spines had grown 

 considei-ably, both in length and rigidity, and the larva remained still after this for 

 two and a half hours longer. The second larva gave me the opportunity of verifying 

 these observations on May 27th, commencing its last moult at 5 p.m. on that day, 

 and behaving in precisely the same fashion ; and when I saw the front legs held back, 

 and again dropped forward with the natural motion of relief, after being freed from 

 the old skin, I was reminded of the familiar manoeuvre of one's being helped off 

 from behind with the sleeves of a tight overcoat. This second larva had fixed itself 

 on only a part of a leaf, too nan-ow to admit of any stepping forward, but it knew 

 how to meet this difficulty, for, when the sloughing arrived at the first ventral legs, 

 the larva fidgctied a little with the anterior legs, but finding nothing they could 



