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MEMOIRS NATIONAL ACADEMY OF SCIENCES. 



Vol. XII, 



they are slender, not stiff or thickened at base, and are spinulated, the spinules short and 

 acute; under a half-inch objective they appear, not bulbous, but tapering, and being transparent 

 may be glandular. 



The single median tubercle on the eighth abdominal segment is sometimes 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 ninth abdominal segment, and, as generally in 

 the group, two short but large ones on the tenth, 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 S. cecropia. The abdominal feet bear 14 crotchets. 

 Before the first molt the larvae 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 between 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 molting it leaves behind 

 it only a small mass of crumpled 

 skin, as the cuticle is so thin. 



Figure 30, a, dorsal tubercle on 

 second thoracic segment ; b, the same 

 on the third thoracic segment; c, a 

 subdorsal tubercle of the seventh 

 abdominal segment; d, a seta; d', 

 d" , ends of two others. All stage I. 

 Drawn with the camera. 



Stage II: One had just molted, 

 June 17. The body was all yellow 

 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 20 minutes or half an hour after molting, 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 crossing the head appears ; in 50 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 tenth abdominal 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, had 

 become dark at the tips, but the hairs were still pale. About a day later, i. e., at 5 p. m., the 

 tips of the tubercles only were dark, the bases being still pale yellow as before. 



This stage differs but little from the first, chiefly in the pale honey-yellowish head; there are 

 as yet no differences in the size of the dorsal tubercles, though they are in this stage pale yellowish 

 at the hase, where before they were black throughout. 



Stage III: They molted again, June 22-23. Length, 14-15 mm. The body is of the same 

 yellow hue as before, the tubercles at first being all yellow. The lateral ones are the first to turn 

 dark. The head is pale yellow, concolorous with the body. 



In the preceding stage, on each abdominal segment there is an upright faint short blackish 

 stripe behind the spiracle; in the present stage there is a jet-black stripe, which is somewhat 

 curved or excavated on the front edge; there is none on the prothoracic segment, and the stripe 

 is represented on the second and third thoracic segments by an irregular black rounded dot. 



