SO:\tE NOTES ON THK PUI'AL MOULT OF LEPIDOPTEUA. 187 



4tli, ')lli, (itli aiu'l Ttli abdominal sccfments arc, immediately on moulting, 

 wide oval opcninf^s, as is that on segment 1, when the wings are turned 

 up to expose it. AVith a lens, it is easy to look into the trachea 

 as far as where the circular oi)enings of one or more branches can be 

 seen ; the place, in fact, where the spiracular trachea joins the longi- 

 tudinal trunk and gives ott' a bunch of I)ranches. At a deptli from the 

 outer ojjening e((ual to about its widest diameter, is a narrowing or 

 second ()i)eniug marked by a narrow semilunar In'own chitinous piece, 

 running round, or rather, across, the anterior surface of the tube, with 

 its free edge just standing out int(t the lumen of the tube. Opposite 

 this, posteriorly, one sees notinng at first, l)ut, at intervals, a thin fold 

 from the posterior surface passes forward and meets this chitinous 

 margin, closing the tube. At first the closing lasts only a second, and 

 it renuuns open for five or six seconds, but gradually the intervals 

 l)ecome more e(}ual, and before the observation ceases the period of 

 closure is rather the longer. The observation ceases because, in about 

 ten minutes, the anterior and posterior lips of the external opening, or 

 spiracle proper, become, by gradual approximation, very close together, 

 so close that, knowing what is going on, one can still see that it is 

 continuing, but still so little, that, without that knowledge, little or 

 nothing could be made of it, and in from 15 to 20 minutes even this 

 amount of view is shut out, and the outer spiracle is (juite closed. In 

 another 24 hom"s or so, this sinks into the bottom of a de])ression, such 

 that, except in a very good light, one cannot see it at all, and might 

 fancy the s])iracle was simply a wide patent (jpening. 



(Observation of another ])upa of /'. hucepluda began when the larval 

 head had reached the 10th segment. The wings are now at end of ;ird 

 abdominal segment — the incision between 3rd and 4th is very mobile — 

 between 7 and 8 not so. After i) minutes, spiracles 2ud, 3rd and 4th open, 

 valve movements being very plainly visible, especially in 4th ; s])iracles 

 5th, ()th, 7th (al)d<)minal) nearly closed. After 12 miiiutcs, 2ud and ;ird 

 closed, valve period = 2 seconds open, 2 seconds shut. The greater length 

 of al)domiual segments 4th, 5th, (ith, 7th, is due to the intersegmental 

 membrane being ex})osed. At the end <f 15 minutes the wings are 

 A of the wav down Ith segment, movement within the spiracle of 4th seg- 

 ment st ill visil )le. After \ i) minntes, movement in 4th still visible, period 

 2 seconds open, 4 shut. After 2() min/ites, 4th (juite closed. 



In another si)ecimeu, three minutes after the vermicular movement 

 of the larva was first noticed, the tracheju were seen being drawn out of 

 7th and 8th aljdomiual segments. .Ifter 5 minutes, the skin split above 

 prolegs between the 5th and (ith abdominal segments, the skin still 

 unmoved on the 4th abdominal, i.e., last six segments of pupa occupy 

 i)th and loth (5th and (ith abdominal) of larva. After 8 minutes, the 

 .skin splits between the 4th and 5th abdominal ahove ])rolegs. After 

 10 minutes, it splits between the 3rd and 4th abdominal {i.e., in the 

 incision, but longitudinal in line above prolegs). After \\ minutes, 

 it splits between the 2nd and 3rd, the skin on the 2ud hardly moved 

 down at all, the Oth abdominal segment having reached end ol" })n])a. 

 After 13 mi)iutes, split between 1st and 2nd abdominal. .Ifter 

 ](') minute.<i, trachi-a being drawn from 1st abdominal s])iracU' ; (he 

 skin of the 4tli abdominal segment reaches c-nd of ])ui)a ; the skin 

 splits dorsally down 2ud, 3rd, 4th (thoracic segments) ; lalei'al s|tlit con- 

 tinuous through 4th, 5th, (Ith and 7th (metathorax aud lirst three abdo- 



