PIERIS. 323 



are easily distinguished by their markings. On placing together, 

 side by side, series of males and females of this species, it was dis- 

 covered that there was a sexual distinction in the cut of the hind 

 margin of the secondaries ; it consists in the female having the 

 outer angle more prominent, and so the whole hind margin less 

 regularly curved, or, as it might be expressed, more flattened 

 these differences, though slight and requiring a careful examina- 

 tion, hold persistently in all species of Pieris I have examined. I 

 have in several cases tested it carefully, by separating, upon this 

 characteristic, the specimens of those species which exhibit two 

 classes of individuals with distinct markings, and have in all cases 

 found the markings to be coincident unequivocally with the cut of 

 the wing. It will be seen, however, that in all the species it does 

 not hold, as in P. protodice, that the female is the darkest. 



Two of the species I have described from Western America, P. 

 venosa and P. pallida, represent respectively the P. napi and P. 

 rapa of Europe. It will be noticed in the European species that 

 each has the same plan of ornamentation upon the upper surface 

 of primaries, namely, a large apical and small submarginal central 

 spot, and that the peculiar distinction between the two is found in 

 the presence or absence of the dark scales bordering the nervures 

 of the secondaries. Just so is it in the Western American species, 

 separated most characteristically from one another by the same 

 distinction in the under surface of the secondaries, and linked to- 

 gether in the same way by certain characters of ornamentation 

 (which, however, are not borrowed from its European congeners), 

 that is, by the presence in the males of the bent band of the inner 

 margin of primaries, and a small submarginal central spot. But 

 when we turn to Eastern America we find this striking circum- 

 stance, that P. oleracea, within its own wide range of variation 

 represents both P. rapce and napi of Europe, and both, P. pallida 

 and venosa of the PaciGc coast ; and what do we discover here, 

 but that, discarding the strict lines of demarcation which separate 

 alike P. rapce and napi and P. pallida and venosa, it follows in- 

 stead, with remarkable similarity, the range of variation discover- 

 able in P. protodice, as before described, a species much farther 

 removed from it in the genus than are they, thus simulating rather 

 its geographical neighbor than its nearest congeners. 



P> frigida and P. marginalis appear to have no true represen- 

 tatives. 



SCDDDER. 



