42 



Female Ckeimatobia to the entirely wingless Anisopteryx. The facts are simply 



here recorded. The causes which have led to such fundamental secondary 



sexual differences arc interesting subjects for speculation. 



In the genus Lobophora, the^nales are distinguished by the large lobe, or 



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



Calocalpe undulata ami the species of Scotosia, the males are distinguished by 



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



tul't 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, lucre is a tendency 

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

 unlikely that many species of this family will ultimately be 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 epiestion 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 opinions varying with the number of specimens and the geographical 

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

 we know the life-histories; though often the larva 1 vary much, while the imago 

 is stable. 



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

 will have to he modified. The number of so-called species tends to be reduced 

 as our specimens and information increase. 



The genera, also, are as artificial creations as species and varieties. The 

 work of- the systematic biologist often amounts to little more than putting 

 nature in a strait-jacket. 



In some genera, as Hyperetis and Boarmia and others, scarcely any two 

 specimens, as they exist 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 no 



