METAMORPHOSIS IN LEPIDOPTERA. 9 



together, now began to alternately relax outwards and contract again 

 inwards close to the body, in what soon became a regular recurring- 

 rhythmic movement, in unison with the heavings of the breast, until 

 within 25 minutes of the event expected, when suddenly most violent 

 writhings and rapid twistings ensued for the space of two or three 

 minutes, and then the slower measured movements were resumed ; the 

 skin enveloping the head became glistening, and throbbed in parts 

 with a slight inflation, in accord with the general heaving action of 

 the larva ; presently a series of very violent struggles occurred with 

 the anterior legs extended laterally ; these efforts proved effectual, for 

 then, at 11.35 p.m., the expected moment came, when the skin 

 suddenly burst all round the throat, as it seemed then to be, close to 

 the old headpiece. Immeditely there appeared a transverse yawning 

 rent, exposing the whitish head and tender glistening bases of the 

 short first pair of legs, held back at the moment by their sheathings of 

 old skin, which drew quickly from off them, when they fell forward in 

 their natural position ; the same measured heaving to-and-fro move- 

 ment continued with incessant energy as the old skin (rapidly 

 blackening) drew back and next exposed the basal joints of the second or 

 longest pair of legs, whose long femora were soon uncovered, yet, 

 before their tibia? were freed, the third pair of legs, being a little 

 shorter and of unequal lengths, were drawn out from their sheathing 

 and slipped forwards, first one, the shorter of the two, then the other ; 

 next were liberated the tibiae and tarsi of the long second pair, all 

 playing immediately after in unison with the whole body, which, now 

 unbending, sustained its hold of the twig by one ventral proleg only of the 

 fourth or hindmost pair, and while the old skin glided back by degrees, 

 the other ventral legs were, in turn, stepping out as it were of their 

 old stockings ; • at this time the long crustacean-like legs began 

 impatiently to play about and push at the old headpiece as cleverly as 

 arms and hands, to weaken the attachment and free the mouthparts, 

 and, from them, the old helmet fell away just as the second pair of 

 ventral prolegs was uncovered. Meanwhile the hinder segments of 

 the body had become drawn out straight and narrowly cylindrical, 

 though tapering, the caudal filaments drawn close together, forming 

 apparently but one projecting point, which now, with the hinder 

 portions of the body, became elevated almost perpendicularly as the 

 foreparts with the head and anterior legs were lowered, whilst the 

 larva was evidently feeling for the adjacent leaf (which had been cut 

 away) ; the third pair of ventral prolegs were next uncovered, and 

 then one of the fourth pair . . . followed by the only supporting 

 proleg, the shrivelling skin then drew off the 11th (? 7th abdominal) 

 segment . . . For two minutes the larva remained perfectly still, 

 and then turned partly round and vigorously thrust and pushed with 

 its mouth and arm-like legs at the old collapsed skin on the 12th (? 8th 

 abdominal) segment which soon became freed, excepting the caudal 

 filaments hidden within the retreating skin. The larva noAV lay at full 

 length, with hinder segments slightly turned aside, all the ventral 

 prolegs sprawling, the anterior (true) legs being extended forward, 

 motionless, for 14 minutes ; it then vibrated the front legs a little and, 

 slowly turning its head round, threw out the longest pair of arm-like 

 legs beyond the head, one bent partly over the other . . . and 

 rested for four minutes more ; it then shook the tail segments, which 



