166 PROCEEDINGS OF THE CALIFORNIA 



cate and unsatisfactory. In Lepid. Heteroc. et Bhopt., No. 8, Mr. H. Strecker 

 has advanced the idea that P. venosa and P. castoria, Reakt., are one and the 

 same thing, and that they are simply the American forms of the European 

 P. Napi, and I can, after an examination of many scores of specimens, but 

 simply endorse his views. That venosa and pallida, Scud., = castoria, 

 Reakt., are at times represented by widely differing varieties no one can deny, 

 and if we take the extreme forms we should naturally regard them as distinct 

 species; but intergrades may always be found, and among these intergrades 

 we find what Scudder designated as pallida, which more nearly approaches 

 Reakirt's type of castoria than it does that of Scudder's venosa. But the 

 insects are not, as has been suggested, spring and summer generations, as 

 they are both found together, appearing in early spring (sometimes in Feb- 

 ruary), and continue on the wirjg until the end of April or the beginning of 

 May, when they begin to die out. But admitting P. venosa and P. pallida 

 to be forms of the same species, what becomes of P. oleracea? Among my 

 specimens captured during the present year, as well as others taken in Col- 

 orado, Oregon, Vancouver Island, and Northern California, are some which 

 continue the series of intergrades until they are merged into the exact coun- 

 terparts of the Atlantic species of P. oleracea, and cannot be in any way 

 distinguished from the well known species of the Eastern States. Is P. 

 oleracea, then, but another form of a trimorphic or polymorphic species? 

 Then, again, many of the individuals of P. pallida approach very closely (so 

 closely as to suggest the very nearest relation), others of P. Rapo?, and the form 

 described by Mr. Scudder as P. marginalis, and afterwards by Mr. Reakirt as 

 P. Yreka, can sometimes scarcely be distinguished from the varieties of pal- 

 ida, upon which Reakirt founded his castoria. Do not, then, our American 

 examples serve very powerfully to prove the common origin of all these forms, 

 and show that we have hitherto attached too much value to what is designated 

 a species, believing certain characters to be permanent, when, in fact, they 

 are so only under the light of our limited knowledge? To illustrate more 

 clearly my meaning, let us take a strongly marked and darkly colored speci- 

 men of P. venosa as our starting point, and we shall pass through the various 

 stages thus, our insects becoming paler, and with the markings less pro- 

 nounced, as we proceed. 



1. P. venosa. Scud. Veins of underside of secondaries, broadly bordered 



with black scales; the lines of equal width to the mar- 

 gin of the wings. 



2. Veins narrowing at the margin, with the ground color 



of the wings more yellow. 



3. Hulda. Edw. Veins with their accompanying black scales, sometimes 



becoming confused, and spread over the whole surface; 

 the lines of scales being sometimes quite indistinct, 

 at others well marked and approaching the following : 



4. Napi. L. Surface of secondaries, yellow, with the nerves bor- 



(Germany.) dered by black scales, the lines being narrower as they 



near the margin. 



