no. i. BOMBYC1NE MOTHS OF NORTH AMERICA— PACKARD. 275 



On the eighth abdominal segment, in place of the atrophied caudal horn, is a low incon- 

 spicuous tubercle, at the apex of which is an indistinctly double ( ?) little wart. 



On the ninth segment are two slightly full, low swellings with seven or eight short minute 

 setae, indicating that they were the site in the ancestral form of this genus of two horns, warts, 

 or tubercles. 



Suranal plate black at the end, which is somewhat rugose. Surface of plate whitish; on 

 the sides and behind pale straw-yellow. On the site of the two horns of t"he previous stages are 

 two rounded conical black tubercles which are more solid and chitinous than those in front, and 

 more like vestigial horns. 



On the side of the segments is a black spiracular very irregular and much broken line, the 

 spiracles being black; above this line on each segment arc three black spots forming an oblique 

 line, the most anterior spot (forming the upper end of the line) being near the front edge of each 

 segment. On each abdominal segment except the tenth (suranal plate) are two black dots 

 situated near the front edge of the segment. Below the spiracular line the body is deeper, 

 almost orange-yellow. 



Thoracic legs pale, with black rings and spots, mid-abdominal legs dull livid green with a 

 black narrow wing at the base, and another one above the planta. 



Underside of the body deep salmon red, with an irregular black line on each side, and on 

 this lino and in toward the middle of each segment are small setiferous black tubercles, white 

 at the apex, and giving rise to a very short seta. Anal legs fairly large, ami sphingiform. 



Habits. — The larva is active in its movements; when rudely poked or handled it will sud- 

 denly jerk its head as if offended, and eructate a portion of its partially digested food. It assumes 

 a decided sphinx-like attitude. 



Its larval life extends over about five or six weeks or 35 to 45 days. It molts four times; 

 the first stage occupies about 9 or 10 days, the second about 6 or 7; the third and fourth stages 

 about 4 or 5 days; and it remains in the last stage about a week (7 to 9 days); the eggs hatched 

 May 27, and one larva pupated June 11-12. 



Acceleration of characters after stage I. — It is to be observed that the armature and coloration 

 are the same in stages II-IV. It is a rule in Ceratocampidse and Saturniidse that the characters 

 of the last stage are not assumed until after the second molt, but here those of the penultimate 

 stage are assumed after the first molt, and in stage IV there is no sign of the atrophy of horns, 

 and of the color differences of stage V. 



The larva malodorous and its colors warning. — Larvae of the. last stage on being handled 

 were observed to emit a peculiar strong odor, a little like musk, and they did so«on several occa- 

 sions when disturbed or handled. 



This fact, that the larva throws off a bad smelling or repugnatorial odor, and that it also 

 vomits its food on being disturbed, should be coupled with the fact that it is a conspicuously 

 marked caterpillar in all stages of existence, both when ornamented with long horns at each end 

 of the body, and when after its last molt it is smooth-bodied, without even a caudal horn. The 

 caudal horn of the earlier stages shows no sign of a bituberculous origin. 



Analogies to Ceratocampidse and to Sphingidse. — On a first glance at the moth one would 

 naturally suppose that it had no relationship to either of these two families; the shape and 

 peculiar markings of the wings are so unlike any of them, but a knowledge of the early larval 

 stages, and of the pupa, with its subterranean habits, led us to examine its structures and 

 affinities, and at first we supposed that this monotypical group had descended from the Cerato- 

 campidee and forms a side branch. 



The larva in its third and fourth stages closely resembles that of Arsenura in the same stages, 

 while the larvse of the two genera are similar in the final stage V, but these resemblances are only 

 analogies, not true affinities. 



A pair of locomotive tubercles or claspers on the second abdominal segment. — Mr. Joutel has 

 called my attention to a pair of soft tubercles or claspers on the second abdominal segment 

 "which is thrust out and seems to be used in walking as though it were a clasper." 



