232 MEMOIRS NATIONAL ACADEMY OF SCIENCES. vol. xii, 



The apical zigzag white line is not so definitely marked and the points between the scal- 

 lops are not so sharp as in the <? of C. promethea. In one o* (Clark collection) from Rhode 

 Island the discal spot of the fore wing is slender and elongated and pierces clear through the 

 extradiscal line. 



It thus appears that the s angulifera varies in its degree of resemblance to C. promethea 

 (being in one similar in hue to 9 promethea) but generally much darker, the tints being chest- 

 nut brown, and approaching <? vromethea, but still differing notably, especially in the fact that 

 the shade beyond the extradiscal is decidedly fighter than in C. promethea. No case of a decided 

 intermediate form has yet been found. 



Female. — Wings broader, not as falcate as in the o* . Body and wings ochreous, much 

 more so than in 9 promethea, with a pink or lilac tinge beyond the extradiscal fine and at the 

 base of the hind wings. Fore wings with the white basal line distinct, edged externally with 

 black, but the fine is diffuse. Extradiscal line more deeply scalloped and the points between 

 the scallops sharper than in the <? of promethea, and the line is bent more, ending nearer the 

 middle of the wing than in 9 promethea. 



The scallops of this line on the hind wings are deeper, more marked than in C. promethea. 

 The discal spots in both pairs of wings are usually much larger than in C. promethea 9 , being 

 trigonate T-shaped, extending from vein II to median, either not reaching or extending clear 

 through the extradiscal fine. The two fines (extradiscal and basal) vary in distance apart. 

 The submarginal fine and spots of the hind wings are much as in C. promethea, those in the 

 anterior part of the wing being broken up into seven separate spots, with two dumbbell ones 

 behind. 



Subapical ocellus as in 9 promethea, but slightly smaller than in two 9 promethea. The 

 white apical fine as in the 9 of the other species. Beneath, the wings are chestnut red on the 

 basal half, especially of the hind wings. Almost exactly like a 9 of promethea, but usually 

 it is more ocfierous beneath. 



Expanse of wings, 9 96-104 mm.; length of wings, 49-55 mm. 



While the 9 differs mainly in color, being more ochreous, and the discal spots larger, the 

 o* differs still more; and yet the two forms might be considered as varieties, or angulifera an 

 offshoot of promethea, were not the larvae so distinct. 



Has C. promethea originated from C. angulifera, and is it phylogenetically the younger of 

 the two forms? 



In 1897 Mr. A. G. Mayer, to use his words in Psyche, February, 1900, showed that the 

 "melanic color of the male of this moth is phylogenetically newer than the color-pattern of 

 the female." 



I have also independently supposed that this must be the case. The melanic male of C. 

 promethea is paralleled by the dark male of Saturnia pavonia-minor, and which I have instanced 

 as a case of female preponderance, or gynerhophy. The facts regarding the latter case are 

 set forth above. In this case we have four species, one of which differs from the three others 

 in having a male with darker fore wings and deep ochreous hind wings, forming a striking 

 departure from the typical style of coloration in the other three species. In the present case 

 we have in a genus with two species only a wide departure not only in coloration but in the 

 shape of the wings. 



Life history. 



The larvae hatched on July 6 and 7 from eggs kindly sent me by Miss Morton, and fed on 

 the leaves of the tulip tree, stages II to IV, are described from Mr. Bridgfiam's colored figures. 

 Miss Caroline G. Soule describes the five stages in Psyche, Vol. V, p. 260. 



Egg. — Of the same shape and color as those of C. promethea, though slightly smaller, while 

 the polygonal markings appear to be even fainter than in C. promethea. 



Freshly hatched larva. — Length 4 mm. The head is black, with two lunate ochreous yellow 

 spots on the vertex, while in front, on the middle, is a transverse, pale parchment-colored stripe, 

 and in front of this stripe is a transverse, clypeal line of the same pale hue. The body is pale 



