74 



VARIATION IN EUROPEAN LEPIDOPTERA. 



of living organisms of comparatively high order, subject to triple 

 transformations, exposed to a wider range of complex natural external 

 conditions (by reason of their powers of migration by flight) than 

 most others, and far exceeding all in number and diversity of species. 



Let us, in the first place, take a glance at some groups of Lepidop- 

 tera which challenge retrospective inquiry into their past history. 



Every intelligent observer of Nature will, in process of time, be 

 brought face to face with the fact that there are, apparently, always 

 two controlling forces at work among living organisms. One is the 

 law of persistence (which is Darwin's law of inheritance); the other, 

 the law of variation (which is Darwin's law of divergence of character.) 

 The question which meets the observer on the threshold of his 

 investigations, is whether variations ever exceed the limits of species, 

 so that one type merges by imperceptible gradations into another; 

 and if this be admitted as undeniable, then he has to consider 

 whether even generic distinctions form inexorable limits to variation. 

 The solution of these problems is to be sought in patient and 

 reverent investigation of the works of the Almighty, and not in dog- 

 matic speculation for or against any preconceived opinion. Now, 

 there are certain genera of Lepidoptera which, by the difficulty they 

 offer in the way of specific determination, seem to point to the con- 

 clusion that originally they have diverged from but one or two parent 

 stocks ; bearing, as they do, so close a family likeness. 



There is, for instance, the family of the Hesperiidae, or 'Skippers,' 

 the most difficult group to study of all the European Rhopalocera. 

 In England there are but seven species, six of w^hich belong to well- 

 characterised genera. But Alveolus^ 'the Grizzled Skipper,' alone in 

 this country represents the genus Syricthus, comprising (to say 

 nothing of varieties) fifteen or sixteen European species, of uniform 

 black and white pattern, over whose distinctions the most celebrated 

 entomologists, past and present, have disagreed and wandered in a 

 labyrinth of chaotic synonyms. Boisduval writes, ' The confusion is 

 so great that it is much to be desired that no further species may be 

 described'; while Dr. Staudinger, in his Catalogue, enumerates no 

 less than six questionable synonyms and descriptions of one species 

 and its supposed varieties. When, therefore, the English collector 

 looks at our little chequered insect, he may be grateful that its 

 parents-in-law and a horde of blood relations were not introduced 

 with him into this island. 



The next group I shall instance as bearing strong cumulative 

 evidence that what are now very distinct species were ancestrally 

 allied, is the genus Erebia, only two representatives of which, fortun- 



Naturalist, 



