the Charlonia group of the genus Anthocharis. 529 



collector took it at the same time as Pech did. Dr. 

 Staudinger did not find it during his expedition there 

 the year before last. 



The distribution of the several species is therefore — 

 Yellow Group : N.W. India ; Armenia ; Algeria ; Canary 

 Isles. White Group : Askhabad ; Turkestan ; N. Persia 

 to Armenia and Algeria. 



Consequently Armenia and Algeria are overlapping 

 areas. This discontinuity is very peculiar, and I will 

 therefore review all the data which I have been able to 

 obtain, and see how it can be accounted for. 



We find both the white and yellow forms inhabit the 

 same line of country, the most distinct species being 

 found furthest east and west, both being yellow ; whilst 

 the two very distinct white species, Tomyris and Pechi, 

 are likewise found to obtain within a limited area 

 almost as far from each other as their yellow allies. 

 The varieties taken in the intervening localities are in 

 each instance a sort of connecting-link between the 

 extreme forms. 



To obtain the desired evidence it is necessary to go 

 back to the early Tertiary times, and see what Geology 

 teaches us. At this period a tropical or subtropical 

 climate extended from the Pole to the Tropic of Cancer 

 with but little variation. The temperature then began 

 to decline gradually, till it culminated in the Glacial 

 Epoch, with which the Quaternary Era opens ; this 

 refrigeration was followed by a secular increase of 

 temperature, which is supposed to have continued with 

 comparatively unimportant variation to the present day. 



We must now look to the fauna of those days for 

 assistance, the Mammalia of which will be sufficient for 

 our present purpose. 



In a gravel- bed near Madrid the remains of the striped 

 hyaena and elephant, both African animals, have been 

 discovered. The bone-caves of Gibraltar have yielded 

 many species, such as the lion, lynx, spotted hysena, and 

 serval, the two latter being now only found in Africa. 

 The Sicilian bone-caves have also yielded the elephant, 

 lion, and spotted hyaena. 



The hippopotamus {H. major) lived in England, France, 

 Spain, Sicily, Italy, and Africa ; whilst, curiously, an 

 extinct South European elephant {E. meridionalis) has 



