VI PREFACE. 



again divided into such as repeat themselves almost constantly, 

 as, for example, Argynnis paphia v. valesma ; and into such as 

 only occur occasionally. 



2. Varieties, or local races. Example: Erebia epiphron v. 

 cassiope. 



3. Darwinian species. In this class Dr. Staudinger includes 

 all those forms about which he was doubtful as to whether they 

 were distinct species or not. Example : Noctua f estiva v. conflua. 



I am inclined to consider all varieties not abnormities as 

 incipient species, or, put into other words, that the occasional 

 aberration, the permanent local variety, or the Darwinian 

 species, are but stages, as it were, in the ultimate production of 

 distinct species. It may happen, and undoubtedly does happen, 

 that a variety never passes the occasional or aberrant stage, 

 because the nature of its surroundings, or other incidental 

 circumstances, may not be favourable to the perpetuation of 

 such variety. On the other hand, a variety only met with rarely, 

 and in consequence considered an aberration, may, in a com- 

 paratively short time, become a local form or race, as, for 

 instance, in the case of Amphidasys betularia v. doMedayarut. 

 This form was almost unknown some thirty years ago in the 

 neighbourhood of Manchester ; now it is to be obtained in 

 numbers there. 



I have omitted from the body of the present list a few species, 

 which have hitherto found a place in former lists of British 

 Lepidoptera. The suppressed species have been arranged together 

 under the heading of " Casual or Accidental Visitors." In thus 

 setting apart these species it must not be inferred that their 

 actual capture in this country is questioned, but it implies that 

 further information respecting them is necessary before they can 

 be considered indigenous. 



Take Chcerocampa nerii for example. This is a common 

 insect throughout Africa, and its range extends into the southern 

 parts of Asia and Europe. In Central Europe it is a great rarity ; 

 and although single examples have at intervals of several years 

 certainly been captured in the British Islands, and even as far 

 north as Finland, such occurrences are phenomenal. 



BICHAKD SOUTH. 



LONDON, April 7th, 2SS4. 





