208 MEMOIRS NATIONAL ACADEMY OF SCIENCES. vol. xii, 



The body is of a soft, pale greenish yellow; the tubercles pale yellowish, contrasting with the color of the body. 

 The prothoracic segment flares in front, the edge turning up and bearing two large dorsal tubercles which are double. 

 The prothoracic tubercles are very prominent, projecting on each side, and are about twice as large as the second and 

 third thoracic ones, and bear twelve bristles. These tubercles and those of the same series on the ninth abdominal 

 segment are much larger than the intermediate ones. There is a slight differentiation in size and color of the dorsal 

 tubercles, those of the thoracic and ninth abdominal segments being of the same size, and larger than those on abdominal 

 segments 1 to 7, and also of a deeper yellow shade. The bristles are pale, those on all the thoracic tubercles, dorsal and 

 lateral, a little darker than those on the abdominal segments, and darker at the tips. They are but little longer than the 

 tubercles, a nd there are about six on each abdominal tubercle. Under a half-inch objective the bristles are seen to be 

 not only docked at the tip, but the latter is slightly but distinctly swollen or bulbous, and sometimes containing an 

 oval mass of the coagulated secretion. 



The median dorsal tubercle on the eighth abdominal segment is as large as those on the thoracic segments; it is 

 twice as wide as long at the base, and is more deeply divided than any other of our Attaci known, very plainly showing its 

 origin from two originally separate dorsal tubercles; each fork is well developed, being about as long as thick, and each bear- 

 ing from four to five bristles. 



All the tubercles of the ninth segment are very large, about as large as those of the thoracic segments. The suranal 

 plate is large, nearly equilaterally triangular, and bears near the apex two tubercles, each of which gives rise to eight 

 bristles; they are smaller in proportion, and nearer together, than those of C. promelhea. 



The prothoracic segment is pale yellowish in front, chestnut-colored behind, becoming blackish on the sides low 

 down. At the base of the lateral prothoracic tubercles are three black rings. On the side of each abdominal Begment 

 1 to 8 is a pair of parallel black slashes, situated between each of the upper and lower lateral tubercles; on the second and 

 third thoracic segments they meet on the middle of the back as chestnut-colored stripes. On each side of the ninth 

 abdominal segment is a large pale yellowish amber tubercle. 1 In some individuals all the tubercles on the body are 

 amber-yellow. 



The thoracic and abdominal legs are pale greenish, with no markings. The thoracic feet bear near the ungues the 

 usual three tenant hairs which are long-lanceolate, and moderately broad. The number of crotchets on the abdominal 

 feet is 24, larger by 8 than in the other Attacidae observed. 



June 17 they had become larger, fuller, and from 9 to 10 mm. in length. The body is of a beautiful soft glaucous 

 green, the tubercles yellowish, those on the prothoracic segment tinged with reddish; the black-brown slashes on the 

 sides of the body are still present, but narrower. They are voracious feeders. 



June 19, at Providence. (Like Mr. Bridgham's second drawing, stage II.) I have not seen them cast their skins, 

 though they must have done so. They are now 11 mm. long. They still retain the black slashes. All the tubercles are 

 yellowish; the body being of a beautiful glaucous green. In some individuals the lateral prothoracic tubercles are 

 reddish. 



Figure 21. Dorsal view of the eighth to tenth abdominal segments of the larva in stage I, showing the double 

 tubercle (d') on the eighth segment (VIII), and the two separate dorsal tubercles (d) on the ninth segment (IX), with 

 the two subdorsal tubercles of this segment (sd), together with the suranal plate (X) and its armature. 



Figure 22. A view of the double dorsal tubercle [d') of the same stage, showing the median line of union of what in 

 embryonic life were probably separate dorsal tubercles, like those on the segments in front and behind; m, the muscles 

 moving the setae; sd, the subdorsal tubercles; m, the retractor muscles of the tubercle; a, one of the seta;, much enlarged, 

 with the bases of two others; a', a", a"', ends of other seta;, containing at the end globules of the medullary fluid. The 

 setae are seen to be smooth, without spinules of any sort. It is to be observed that in the double dorsal tubercle there 

 are only four setae on one side and five on the other, but five must be the normal number, and the number usual in the 

 larvae of the group at this stage. 



Stage II: June 23. Length II to 15 mm. They have most probably molted, the lateral pair of upright parallel 

 slashes having disappeared. The spiracles are now black and very distinct. The tubercles are deep orange at the end, 

 the dorsal ones bearing mostly blackish bristles, with one or two white ones, those on the side of the body being pale; 

 the lateral tubercles are orange, all the prothoracic tubercles deep orange, and the segment itself is edged with greenish 

 yellow orange. The thoracic legs are deep orange; the abdominal legs green, tipped at the plants with yellow orange. 



There is now a lateral curved white band connecting the lateral tubercle on the ninth segment with the corresponding one 

 on the suranal plate. Along the back and between the dorsal tubercles the skin has a soft glaucous bloom. The head is 

 dark chestnut-red, as before. 



In this stage the larvae frequently assume a sphinx-like attitude, while those of P. cecropia and S. cynthia do not 

 seem to, but these two species are in general more active, trying to escape from confinement. 



Stage III : Molted July 1. Length 20 to 25 mm. The color of the head and tint of the body as before. The larva 

 now differs in the segments being more convex and angular, or in tranverse section somewhat square, somewhat as in the 

 last stage. All the tubercles are alike in being pea-green at base, becoming deep reddish orange at the end, and bearing 

 partly black and partly white spines or bristles, except the two median short tubercles on the prothoracic segment, 

 which are yellow, and concolorous with the yellow margin of the whole segment. There are more white bristles on the 

 abdominal than on the thoracic segments. 



1 In A. luna (he suranal plate is triangular, but slightly shorter than in T.polyphtmus, the two tubercles are wider apart, not so near the end of 

 the plate, and am much lower and flatter, while those of T. polyphcmus are quite high and slender, papilliform. 



