160 THE BL'TTERFLIES OF NEW EXGLAND. 



would I)e conclusive if the coiiii)lete [);irentaue in each case were known ; 

 but as only the niotlier wa,s known in any case, another explanation is 

 not only possible, but in view of all the facts probable. The mtergrades 

 found throughout the belt forming" the northern boundary of the typical 

 alo[)e and the southern boundary of the typical nej»hele seem to be far 

 more easily ex[)lanable on the hy[)()thesis of hybridism, since they occur 

 only where such a })]ienomenon is possible, and wherever it is [)ossible. 

 The same argmnent a[)[)lied to the case of l>asilarchia, as has been done 

 by Edwards, Avould logically [»roAe more tlian he would agree to, \'v/,. : 

 the specific identity and trimorphism of all the eastern S[)ecies excepting 

 B. archippus. That the species of Cercyonis here described are certainly 

 distinct I would by no means maintain; only that in view of the facts of 

 distribution, it seems more })robaI)le that they should be looked u[)on as 

 lining reached in their develo[)ment the stage of specific distinction, 

 while they are readily fertile iufer se and produce intergrades where they 

 meet on conunon ground. It would perhaps be possible by introducing 

 a considerable number of nephele into a southern locality far removed 

 from the "belt of dimor[)hism,"()r, as 1 should rather call it, the " bastard 

 belt " ; or bv the introduction of alo[)e into an ecpially remo^•ed northern 

 locality, to [)roduce in free nature intergrades at those points. ]>ut if 

 such an ex[)eriment failed, it might easily be presumed that the conditions 

 of life were not sufficiently favorable to the introduced form, or that the 

 results were overlooked. It is a difficult ([uestion to settle, I)ut the 

 progress of experiment and research will doubtless one day determine the 

 matter. 



The butterflies of this genus have am[»le wings of a uniform rich dark 

 l)rt)wn above, the outer margin pencilled with two or three darker lines 

 and preceded by a few (on the fore-wings by one, or two; on the hind- 

 wings generally I)y one) darker ocellated spots, usually confined to the 

 lo\\'er subcostal and lower median interspaces ; those of the fore-wings 

 are sometimes enclosed in a broad yellowish band ; beneath, the wings 

 are irrorate with short dark streaks on a lighter brown base, the markings of 

 the up[)er surface are repeated and, on the hind wings, often accompanied 

 by additional occellated s[)ots, not ecpiidistant from the outer border. 



There is but a single brood each year, the butterflies flying from mid- 

 sunmier onward and the caterpillars hibernating as soon as born, as in 

 the allied Euro[)ean genus ]\Iinois : the chrysalis is attached by its hinder 

 extremity to blades of grass, etc. 



The eu'irs fire short barrel-shaped, furnished with numerous lonaitu- 

 dinal ribs. The juvenile cater[)illars are stout and furnished with exceed- 

 inglv long. com|)ressed, geniculate a[)pendages, bent l)ackward, excepting 

 those of the doi-sum of the thoracic segment, which turn forward pre- 

 senting a [)eculiar contrast. The mature cater[)illars are simply [)ube8- 



