v iii INTRODUCTION. 



recognised local races are, in fact, forms very much intensified com- 

 pared with the Continental race. Striking examples of this character 

 are seen in British specimens of such species as Viminia euphorbia var. 

 myricce, Dianthcecia luteago var. barrettii, Dianthcecia ccesia var. manani 

 and many others. These are, however, excellent illustrations of 

 distinct local races or varieties, occurring quite independently of the 

 type, and varying inter se as much as does the type in other localities. 



Such absolute cases as these, however, are comparatively rare. 

 Eeference to the general remarks on such species as Agrotts hyperborea, 

 A. subrosea, Tamiocampa instabilis and Pachnobia rubricosa will show, 

 however, that I have not neglected this part of the work. The first two 

 of these species, although having intermediate forms, are strikingly 

 developed as local races in Britain compared with the Continental 

 form. The typical pale hyperborea of Scandinavia etc., is replaced by 

 red forms in Britain and the Alps, whilst the ordinary Continental 

 form of subrosea known as var. subccerulea, is also pallid, the British 

 form being very strongly tinged with rosy. Pachnobia rubricosa gives 

 us local races that cross in various localities, although strongly 

 differentiated in others, so also does Tceniocampa instabilis. At any 

 rate, the general notes on these and other species should be sufficient 

 to direct the attention of future workers to the main facts as to 

 whether, in certain localities, the forms should be considered 

 principally as " varieties " or " aberrations," although I must own that 

 I have not been able to see my way out of the mass of difficulty which 

 must necessarily have occurred, had I attempted to adopt the 

 Staudingerian arrangement, e.g., Tapinostola fulva ab. fluxa of 

 Staudinger's ' Catalog ' would become var. fluxa in many parts of 

 Scotland, just as the Cuspidia psi var. suffusa in London, would become 

 ab. suffusa a few miles out. Leucania lithargyria var. argyritis, as it is 

 called in Staudinger's ' Catalog.' would become ab. argyritis in Britain, 

 where this pale form, far from developing into a local race, is of the 

 most rare occurrence, turning up as an aberration occasionally with 

 the type. Again the Grammettia trigrammica var. bilinea of Staudinger 

 would become ab. bilinea ; Cleoceris viminalis var. obscura, would 

 become ab. obscura in most localities, and so on almost ad infinitum. 



Many of the forms with which I have had to deal, can scarcely be 

 classed either as " varieties " or " aberrations." They have neither 

 developed into "distinct local races which have supplanted the 

 type" since they occur with the type, nor can they exactly be 

 looked upon as accidental forms which occur occasionally with the 

 type, as they are, on the contrary, frequently equally common with 

 the type. The various forms of the species in Leucania, Agrotis, 

 Apamea etc., will immediately occur to lepidopterists as illustrations of 

 this view. 



At the same time I am quite aware of the fact that although a 

 " variety " and an " aberration " may be identical in the cabinet, yet 

 in the hands of the field naturalist, the "variety" will probably 

 breed true, a specimen of the type form only occurring occasionally as 

 an "aberration," whilst the "aberration" may produce some 

 " aberrations " but will in the main revert at once to the type. This 

 appears to be the great difference between them, and the only reason 

 for making any discrimination. 



It becomes evident, therefore, that the division of forms which do 



