OF ARTS AND SCIENCES. 75 



The siugle median tubercle on the 8th abdominal segment is some- 

 times nearly twice as large as the others on the same segment, and is 

 double, being broader than long, bearing four bristles on each side. 



There are two setiferous tubercles on the 9th abdominal segment, 

 and, as generally in the group, two short but large ones on the 10th, 

 being situated on the front edge of the suranal plate, and bearing each 

 eight bristles. All the tubercles on the body are jet-black. 



The spiracles are pale, and inconspicuous. The thoracic feet bear 

 three lancet-shaped tenant hairs, but they are a little wider than those 

 of P. cecropia. The abdominal feet bear fourteen crotchets. 



Before the first moult the larvse increase in size and length 

 (7-8 mm.), becoming much fuller, swollen out with food ; the body, 

 however, is smooth, the segments not being swollen ; it is bright 

 straw-yellow ; the spines are not so long as before, and the bristles are 

 considerably shorter. A dorsal row of dark spots is present. 



Before a change of skin the larva rests immovably for several hours, 

 the membrane in front of the prothoracic segment being swollen be- 

 tween the head and the front edge of the segment, and the head, now 

 appearing to be very small in proportion to the swollen prothoracic 

 segment is held downward, while the thoracic feet are stretched for- 

 ward. In moulting it leaves behind it only a small mass of crumpled 

 skin, as the cuticle is so thin. 



Figure 6 (Plate II.), a, dorsal tubercle on 2d thoracic segment; 

 b, the same on the 3d thoracic segment ; c, a subdorsal tubercle of 

 the 7th abdominal segment ; d, a seta ; d', d", ends of two others. 

 All Stage I. Drawn with the camera. 



Stage II. — One had just moulted, June 17. The body was all yel- 

 low except the dorsal and two lateral rows of black spots between the 

 rows of tubercles, there being two spots in each row on each segment. 

 All the tubercles are now amber-yellow, and the hairs are pale. 



An individual was noticed to increase in length soon after ecdysis. 

 It was observed at 4.20 P. M. In about twenty minutes or half an 

 hour after moulting, when it is 9 to 10 mm. long, the tubercles on the 

 side, especially those in front, begin to turn dark, the thoracic ones first 

 changing color. In about an hour an obscure broad dusky band cross- 

 ing the head appears ; in fifty minutes or an hour, the thoracic legs 

 have turned blackish, and by this time the creature begins to eat, this 

 species feeding well in confinement. In an hour and a half the lower 

 lateral (infraspiracular) row of tubercles and those on the 10th ab- 

 dominal segment had turned black, but the upper lateral and dorsal 

 ones were still pale. By 6.30 p. m. the others, both dorsal and lateral. 



