BUTTERFLIES OF TWO WORLDS. 437 



In the first place, there Is one .speeie.s, Pieris rapue, avIiohc intnKlurticjn 

 into thi.s country is a matter of liistory, and of vvli<j.se innnediate European 

 origin there is tlierefore no question. There arc tlnee others, Euvanessa 

 antiopa, Vanessa cardui and V. atahmta uhich do not vary in tlie shghtest 

 degree from the same species in the Okl A\'orhl, although some writers 

 have at times thought that they could pick out the American and European 

 forms when mixed in the same collection. Euvanessa antiopa is very 

 widely distributed, covering almost the entire North American continent 

 excepting arctic and subarctic lands, and even here it extends within the 

 latter to Alaska. In the Old World it has an equally wide distribution, 

 l)cing found over the whole of Europe excepting southern S})ain, and over 

 all of northern Asia. It is an insect of strong Higlit, and being found upon 

 both sides of Bering Strait, could unquestionably pass from one conti- 

 nent to the other at this point of their nearest approach. In which conti- 

 nent the species originated nuist l)e judged rather from the abundance nnd 

 variety of its nearest allies on the one continent and on the other. In 

 America there is but a single additional species of the genus occurring, and 

 that so rare that I am not aware that more than one specimen has ever 

 been found, occurring as it does in the mountains of Mexico. In the Old 

 World several species occur in southern Asia, bul in addition there is a 

 very closely allied genus, Inachis, which occurs in Europe but not in 

 America, and it is therefore in the highest degree probable that the origin 

 of the species should be looked for in the Old AVorld. As to the two 

 species of Vanessa, we have shown in our account of this group that the 

 genus is divisible into two sections, into one of which cardui falls, into the 

 other atalanta, and that the immediate cono-eners of cardui are found alto- 

 gether in the New World and those of atalanta in the Old. The distribu- 

 tion of these species in the New World being more restricted than that of 

 E. antiopa, so that there is no probability of any recent transfer of forms 

 between the two continents, we are left entirely to the consideration of 

 their allies to judge in what part of the world they originated, and on this 

 basis there can be no question whatever that cardui originated in America, 

 and atalanta in the Old World. 



Two other species are in nearly the same category as the last as regards 

 their distribution on this continent. These are Cyaniris pseudargiolus and 

 Ileodes hvi)0})hlaeas, which many writers are inclined to consider identical 

 with argiolus and phlaeas of the Old World. There can be no doubt of 

 their exceedingly close affinity, nor, on the other hand, of the fact that 

 whether species or variety, the forms existing in the New World can be 

 separated from those of the Old. With regard to Ileodes, there is but a single 

 species of the genus, in its restricted form, in either hemisphere. In each 

 it extends from ocean to ocean, although not found in the high north, and 

 inasmuch as the genera nearest to it are also represented by species in each 



