96 



at all. The dates of capture of Virginicnsis, or when they were 

 seen, but not captured, are recorded in my journal thus : 



The spring of 1870 was cold, and we had ten inches snow- 

 fall on i8th April. In 1871, on the other hand, we had fine 

 weather all through March, and peach trees were in bloom on 

 the nth. Therefore the appearance of Virginicnsis, so early as 

 20th March, 1871, and so late as 15th May, 1870, is accounted for. 

 Strictly, it is an April butterfly, coming with the early flowers. 



No second generation appeared here in these years. In the 

 first place, it is hardly possible that I, myself, should have failed to 

 take or see individuals of a later generation if there were any. 

 One single example during these six years would have served to 

 attest the existence of a second generation. Also, I had boys in 

 my employ instructed to take everything ; and of Virginicnsis sub- 

 sequent to May, or of a second generation, none appeared in their 

 collectings. In the next place, between 1867 and 1872, the late 

 Mr. Ridings, a most indefatigable collector, spent one whole 

 season here, and again the month of September. Mr. Julius E. 

 Meyer, a month in midsummer of two years, and again in Septem- 

 ber. Mr. Mead collected here repeatedly, both before and after 

 1872. All these gentlemen were experts with eye and hand, and 

 thoroughly acquainted with North American diurnals, but no 

 one of them found an example of the second generation of 

 Virginiensis. Therefore I assert with confidence that such a 

 generation has no existence here. 



In 1874, Rapte first made its appearance in this valley. I 

 recorded as follows: 1874, 17th September, " took i $ Rapce, the 

 first of this species ever seen here by me." On 6th Oct., " saw seve- 

 ral Rapm.' In 1875, 8th April, " saw several Rapac^' and from that 

 day to this the species has abounded all the season. I was ab- 

 sent from home from ist April to 15th May, 1873, ^"d so know 

 nothing of Virgi7iiensis that year; but since 1873 I have not seen 

 one example, though I have carefully sought for it in the hope of 

 breeding from the Qg'g, and so learning its history. 



But so long as Rapae is a thousand to one, the weaker species 

 will be overlooked at least, being undistinguishable on the wing 

 among so many white butterflies of same size, and probably will 

 soon become extinct. Perhaps it is already extinct in this locality. 

 I hear from Massachusetts, New Hampshire, New York and Can- 

 ada, the same story of the absolute disappearance of Oleracca 

 where, fifteen years ago, it abounded, before Rapae, had con- 

 quered the country. 



