576 PROCEEDINGS OP THE AMERICAN ACADEMY. 



Under side of the body deep salmon red, with an irregular black Hue 

 on each side, and on this Hue and in towards 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, and sphingiform. 



Habits. — The larva is active in its movements ; when rudely poked 

 or handled it will suddenly 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 35-45 days. 

 It moults 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 (7-9 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 

 Ceratocampidae and Saturniidae that the characters of the last stage are 

 not assumed until after the 2d moult, but here those of the penultimate 

 stage are assumed after the first moult, 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 it did so on several occasions 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 moult it is smooth-bodied, without 

 even a caudal horn. The caudal horn of the earlier stages shows no 

 sijni of a bituberculous origin. 



Analogies to Ceratocampidae, and to Sphingidae. — 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 Ceratocampidae and forms a side branch. 



The larva in its third and fourth stages closely resembles that of 

 Arsenura in the same stages, while the larvae of the two genera are 

 similar in the final Stage V, but these resemblances are only analogies, 

 not true alii ni ties. 



