6(j SAMUEL H. SCUDDER ON THE SPREAD 



it is most numerous and does the most damage. Its parasites then foUoAV it up and its 

 injuries, though still serious, are by no means so alarming. 



I have purposely refrained from mentioning hitherto the fact that, in the opinion of 

 some entomologists, Pieris rapae is indigenous to the Pacific coast of America, or 

 at least has been known there for fidly a quarter of a century and no one knows how 

 much longer. Specimens were first brought east by Mr. A. Agassiz in 1859. It is well 

 known that the butterflies (not to mention other animals) of the Pacific coast are more 

 nearly allied to those of the Old Woi-ld than are the butterflies east of the Rocky Mts. ; 

 and therefore, to one regarding these western Pierids as identical with P. rapae, they 

 may well be looked upon as autochthonous, inasmuch as in the Old World P. rapae ex- 

 tends from the Atlantic to the Pacific, from Great Britain and Barbary to Ivamtschatka 

 and Japan. In his elaborate paper on the American forms of Pieris allied to P. 

 napi of Europe (Papilio i, 83-99, pi. 2-3), Mr. W. H. Edwards has argued that all 

 the American species of Pieris (as I have limited it) which do not belong to the Euro- 

 pean P. rapae, are to be classed with the European P. napi, and in his last catalogue he 

 has so arranged them, excepting that for some unaccountable reason he separates as a 

 distinct species P. virginiensis, which he himself stated three years earlier had given birth 

 in ]Mr. Mead's breeding experiments to the form oleracea. 



This is not the place for the discussion of affinities, so I can only here express my 

 pi'esent dissent from the conclusions of Mr. Edwards, maiidy upon the very grounds set 

 forth in his paper, in which I think he has confounded two distinct species. My own be- 

 lief is that we have in America, in addition to the introduced P. rapae, two distinct au- 

 tochthonous species, each of which shows seasonal dimorphism similar to that of P. 

 rapae, and at least one of them some marked geographical races. One species, gener- 

 ally known as P. oleracea, covei'S the continent from ocean to ocean and reaches from 

 Alaska and Labrador to Central California, Colorado and Virginia. It has been de- 

 scribed under many different names, such as casta, cruciferarnm,marginalis, frigida, hulda, 

 and virginiensis, besides several varietal designations. As a general rule it has no spots 

 upon the upper surface, though these sometimes appear, probably by reversion. The 

 other species, P. venosa, has been hardly less tormented with appellations, having been 

 also christened pallida, yreka, castoria, nasturtii, resedae and iberidis. It is found along 

 the Pacific coast from central California to British Columbia at least as far as Lat. 52° N. 

 It is closely allied to and may be said to represent P. napi in this country. It is, how- 

 ever, as distinct from P. napi as P. napi is from P. rapae, and the only logical outcome 

 from the position assumed hy Mr. Edwards is, in my opinion, to consider all these species 

 of Pieris, — rapae, napi, oleracea and venosa, as different forms of one species. It mat- 

 ters little whether they are lookel at in this light or as distinct species, for they undoubt- 

 edly came from the same stock. The only claim I would make is that if P. rapae and 

 P. napi are distinct species, as they are universally considered in Europe, then the 

 American species, previous to the introduction of P. rapae into eastern Canada, were dis- 

 tinct from the European and from each other. That certain forms of each of them, and 

 especially of P. venosa, might readily be taken (as has been done) fori-*, rapae is un- 

 questionable, and it is possible that the species, seen in 1881 and again in 18SG at Great 

 Falls and the Belt Mts., Montana, was P. venosa, so marked. I have accordingly cov- 



