266 THE BUTTERFLIES OF NEW ENGLAND. 



brooded ; but in not infrequent cases, doubtless more frequent in southern 

 than in northern parts, a second or supplementary brood is formed in one 

 season ; as the butterfly lays eggs for some time, and all the females are 

 not born at once, the earliest progeny of the earliest females may not in- 

 frequently be able to mature in the same season in time for the production 

 of a second brood. This would seem to be a provision on the part of nature 

 to give the species a better chance. That they need it is perhaps evi- 

 denced by the fact that the black-veined orange species, which are almost 

 universally more numerous in individuals than the others, have, in regions 

 where one brood is the normal condition of their fellows, always two broods. 

 But this is not the only advantage the black- veined orange species have, 

 so that we cannot fairly ascribe their greater numbers to this alone. Their 

 very colors are an advantage to them, for in them they mimic species 

 of Euploeinae, which possess a taste and perhaps an odor offensive to 

 bu'ds and other insectivorous animals ; the mimicry is very striking indeed, 

 and is the more remarkable from the fact that the northern species resembles 

 the only species of Euploeinae found in the region it inhabits, while the 

 southern species as well as the southernmost examples of the northern 

 species, resemble another which is more common in the region they inhabit. 

 It is indeed possible that one of the normally colored species of Basilar- 

 chia, one that has least conspicuously contrasted colors, though resplendent 

 with blue and green, is specially protected by the various other devices we 

 have recounted ; for certainly it is itself mimicked by one sex of a butterfly 

 of another very distinct group, viz : Semnopsyche diana. 



Table of species of BasilarcMa, based on the egg. 



Height of egg about live-sixths the width archippus. 



Height of egg scarcely less than width astyauax. 



Table of species, based on the mature caterpillar. 



The minute, smooth, lenticulai* warts very infrequent, not more than twenty above the 

 spiracles on any segment. 

 Coronal tubercle of head crowned with distinct denticulations interrupting the contour 

 above; principal tubercle posterior to it denticle-shaped, many times higher than broad, 



independent archippus. 



Coronal tubercle of head rather regularly rounded at summit, but crowned with raised 

 points; principal tubercle posterior to it tumid, but little higher than broad, compound, 



and at base closely united to the coronal tubercle arthemis« 



The minute, smooth, lenticular warts tolerably common astyanax. 



Table of species, based on the chrysalis. 



Cremaster, viewed from above, twice as long as its apical width archippus- 



Cremaster, viewed from above, less than twice as long as its apical width. 



Basal wing tubercle rounded ofl' or partially suppressed astyanax. 



Basal wing tubercle produced to a minute point directed backward arthemis. 



