22 THE BUTTERFLIES OF THIE WEST COAST 



sion being merely guess-work as to the possibility or probability 

 of any such thing ever happening, and thus, perhaps, accounting 

 for some puzzling intergrades or variations. In this view Mr. 

 W. H. Edwards has written a few sentences, but as nothing was 

 positively known, no conclusions were reached ; and H. Edwards, 

 in 1876, described a butterfly which was thought to be a hybrid 

 between Atalanta and Caryc, but, as before, nothing was posi- 

 tively known. But the opinion has always been advanced that the 

 progeny, if any there were, would be infertile, and so disappear, 

 in the next generation, if not in this. 



And now let us have a couple of facts upon which to base con- 

 clusions. In 1895 I observed a pair of Theclas in copula. As is 

 usual in such cases, they were flying heavily, one flying away with 

 the other, and soon they alighted ; upon taking them I found the 

 male to be Dumetorum, and the female was Iroidcs. Again, in 

 1902, I saw a pair of Pierids similarly attached; they were cap- 

 tured, and immediately mounted ; the male is Rapcr, and the 

 female is Protodice. Thus in seven years I have captured two 

 pairs mismated, in full copulation, and the fact that such mis- 

 matings can and do occur is fully established. During the same 

 seven years I have taken in copula perhaps twenty pairs each year, 

 regularly mated. 



At that estimate one pair in 140 is regularly mismated, or 

 irregularly mated ; at which rate, out of a thousand matings seven 

 would be irregular. Now, if that per cent be normal and con- 

 tinuous, we see at once that there can be no resulting fertile pro- 

 geny from the mismatings, for if there were intergraded varieties 

 following every mismating, the world would be full of hit-and- 

 miss butterflies in a few years. It therefore appears conclusive that, 

 as in other lines of the animal kingdom, the mismatings must be 

 infertile, either immediately or in the next generation. This is 

 one of those cases that can be proved only by the breeding of the 

 egg and the larvae of this year and of next year also, and those 

 difficulties that stand in the way of such breeding are so many 

 and so great that it is safe to say it will be many a decade before 

 it is accomplished ; and he who has bred butterflies knows this 

 very well. 



§ 14. Dimorphism. 



Is a name given to white or black females, which in general 

 color differ totally from their normal-colored sisters. In Colias, 



