904 THK BUTTERFLIES OF NEW ENGLAND. 



furtlier rLMiiavks that its presence or absence sometimes separates closely 

 related species. The European Eiisticiis bellargiis and Lycaena corydon 

 perhaps offer the best examj)lc of this peculiarity, which does not appear 

 to be present in any of our New England species, altliough we possess a 

 species of Kusticus. Tlic tibial bristle is never present in the other tribes 

 of Lycaeninae. 



The Lycaenidi form a characteristic and imj)ortant feature of the butter- 

 fly fauna of Europe and to a certain extent of western Xorth America, 

 especially, in both countries, in mountainous regions ; but they compose 

 an insignificant part of the fauna of the eastern part of our continent and 

 are almost wholly unknown in South America. 



We are not therefore surprised to find that not one of the genera found 

 in New England is of peculiarly American origin, all Iieing also repre- 

 sented in the Old World and on the Pacific coast ; in marked contrast to 

 what we have seen to be the case among the Theclidi. 



The eggs are of a very depressed, echinoid shape, studded with projec- 

 tions connected by delicate raised lines. They are laid singly. The 

 larvae feed upon herbaceous plants, principally uj)on Leguminosae, rather 

 than upon trees and shrubs, as the Theclidi : they taper less than those of 

 the otiier groups. JNIore tlian any other Lycaenidi they are provided with 

 an al)dominal secreting vescicle and caruncles, attractive to ants which 

 become their companions. Fuller details will be given under the species.* 

 Westwood says "the chrysalis is generally attached to the stems of j)lants ; 

 but occasionally this state is passed beneath the surface of the earth." I 

 find no repetition or verification of this latter statement ; perhaps it had its 

 origin in the fa<;t that several P]uropean species are known to half burrow 

 themselves in the ground for pupation, probably the better to secure their 

 fastenings. The insects sometimes hibernate as chrysalids, but occasion- 

 ally as larvae or even in the egg ; never so far as known in the perfect 

 state. Our few species are variable in this respect, and perhaps represent 

 all these types. The number of generations is variable, some species be- 

 ing single, some double, and one of ours even triple brooded. In one of 

 our species, polymorphism runs riot. On the other hand. Baker reports 

 one instance in which pupal life in a European species continued for two 

 years (Ent. monthl. mag., xxii : 90). 



Table of yenera of Lycaenidi. based on the erjg. 



Flat or depn^ssetl jiortion of upper surface searcely half the diameter of the egg. 



Egg less than half as high as broad Everes. 



Egg more than half as high as broad Cyauiris. 



Flat or depressed portion of upper surface more than half the diameter of the egg. .Rusticus. 



(Nomiades not seen.) 



•See a sunnnary of the .s])ocies in which cently printed by me in the Proc. Bost. soc. 

 these two sets of organs occur, in a paper re- nat. hist., xxiii : 357-358. 



