•42 



female C/ir/}natobia to the entirely wingless Anisoptery.r. The facts are simply 



here recorded. Tiie causes which have led to such tiHidamental secondary 



sexual diflereuces are interesting subjects for speculation. 



In ti)e genus Lobophora, the males are distinguished by the large lobe, or 



bubble-like expansion, at the base of the inner edge of the hind wings. In 



Calocalpe undulata and the species of Scotosla, the males are distinguished by 



the large ear-like expansion of the iniier edge of the hind wing, and by the 



tuft of hairs. 



§ 12. — Origin of the genera and species. 



It will be noticed that the tendency in this work has been to unite what 

 some might regard as distinct varieties, or even species, as I have myself 

 done until receiving better material. This course of treatment has been 

 applied especially to the circumboreal species. It has been done in dealing 

 with species described by myself as well as others, so that the work has been 

 performed as impartially as the material would warrant. There is a tendency 

 in some European authors to multiply species unnecessarily; and it is not 

 uidikely that many s])ecies of this family will ultimately lie regarded as vari- 

 eties. At the present day, two methods are in use by evolutionists: one, to 

 multiply varieties, calling them incipient or "Darwinian" species; the other, 

 to unite them. It is sometimes a difficult question what to do. The work 

 should be done on the merits of each case, without being influenced by theory. 

 This would be easy enough to do if the varieties and species were fixed. 

 They often vary so greatly that no two persons can agree on the same species; 

 their opinitms varying with tiie number of specimens and the geographical 

 extent of the area collected from. Our ideas will undergo a revision when 

 we know the life-iiisfories : though often the larva' vary much, while the imago 

 is stai)le. 



My descriptions, then, may be looked upon as provisional, and doubtless 

 will have, to he inodilied. The mimi)er of so-called .species tends to be reduced 

 as our specimens an<l inti)rniati(in increase. 



The genera, also, are as artilicial creations as .species and varieties, "l^he 

 work of the .systematic i)iologist often amounts to little nH)rc than putting 

 nature in a sti'ait-jacket. 



In some genera, as Hi/ppirfis and Boaniiia and others, scarcely any two 

 specimens, as they ('xist in our museums, seem to be alike. Sometimes, the 

 individuals differ so much as to indicate the formation of sports, strains, or 

 incipient varieties It is so with some genera. For example, had we im 



