1893.] LOL [Packard. 



repeated observations, that the great thoracic spines are of real defensive 

 use. 



An examination of Fig. 2 will illustrate better than a prolix verbal 

 description the appearance of the spines in Stages I and II of this species. 

 They are all drawn with the camera, and it is to be observed that the 

 " horns " are more like those of Cither onia regalis than Eacles imperialis. 

 a, one of the horns on the second thoracic segment; a', the extremity 

 enlarged, showing the circular corrugations ; a", the same more magni- 

 fied ; a'", a terminal spine enlarged, showing its mode of insertion ; it 

 contains a central mass of minute globules ; 6, the first abdominal seg- 

 ment enlarged to show the position of the dorsal, subdorsal, supra-spirac- 

 ular and spiracular stripes, the latter enclosing the spiracle ; also the 

 position of the four spines, one dorsal, one subdorsal and two infraspiracu- 

 lar ; the spines are all minutely barbed ; c, a dorsal spine, bearing a 

 spinuieat its base; d, "caudal horn" or media-dorsal spine on eighth 

 abdominal segment ; ix, that on the ninth segment ; it is small, conical and 

 forked at the end, each fork bearing a long seta. All the foregoing in 

 Stage I. /, a "horn" from the second thoracic segment. Stage II; the 

 two terminal spines have entirely changed in shape, being larger and 

 longer, and bearing a tapering fine bristle ; a third smaller conical tuber- 

 cle has appeared near the base of one of the forks. The spinules on the 

 trunk now bear a bristle ; e, "caudal horn " of Stage II ; now large and 

 high, deeply forked at the end ; the spines or tubercles on the trunk ot 

 the horn now bear each a slender bristle. 



Stage i/Z— Molted July 2(j, 27. Length, 13-15 mm. The head is 

 now high, the face subiriangular, not black as before, with a green 

 lateral stripe, but pea-green icith a yellow stripe on each side, shaded more 

 or less with black between the yellow V ; and on the outside, in one 

 example, the black is reduced to a diffuse patch inside, while in another 

 larva it is outside of the yellow V. The head is now nearly as wide as 

 the body. 



The eight horns are still nearly half as long as the whole body and are 

 now paler than before, being reddish chestnut and yellow at base, with 

 black spinules and blackish at the tips, which are now not bulbous, only 

 irregularly forked. The spines along the body are larger and stouter 

 than before ; the tubercles at base are deeper yellow than before, tipped 

 with black, while the high, conical or (sometimes) rounded granulations 

 are snow-white. The lateral yellow stripe along the body is more dis- 

 tinct than before ; it is bordered above with pure white, and above this is 

 the linear dark purple spiracular line, shaded above more distinctly than 

 in the preceding stage with deep blue-green or verdigris green ; the 

 caudal horn as before being pink, with white spines bearing black bristles. 

 The larva also difiers from that of Stage II in the suranal plate, which is 

 more deeply forked, the forks being thicker, larger and with several tuber- 

 cles ; the sides of the plate are heavily spined and on the surface are 

 about six central, small, conical spines. Now the dorsal abdominal 



PROC. AMER. PHILOS. SOC. XXXI, 141. T. PRINTED MAY 8, 1893. 



