DEILEPIIILA GALII IN 1888. 219 



Eiqjithecia vidgata. Generally much darker in London than 

 in other parts of the Kingdom, — E. rcctangidata. A splendid 

 black variety, nigroscrlceata, is abundant in the London District. 

 This is a fine melanic form, the males being of a deep smoky 

 black, the females of a deep dark green, with black markings. 

 It is very different from the type. I have captured a large 

 number of this species in London, but all are of this variety ; the 

 type dues not seem to occur. 



filclanlppe Jliictnata var. neapoUata, Mill. A small proportion 

 of the specimens of this species closely resemble the dark variety 

 named above. 



In other families Botys rurcdis is much darker in the London 

 District than a few miles out ; whilst melanic forms of Clido 

 phragmitellus not infrequently occur. Cramhiis perlellus var. 

 wavringtoncllus is abundant, whilst perfectly melanic forms of 

 Tortrlx podana, Hedya ocellana, and Grapliolitha ncevana are 

 very frequent. A dark form of Xantlioset'ia zoegana is almost 

 peculiar to the London District. Diurnea fagclla is sometimes 

 very dark, almost equalling in depth of colouring the well-known 

 melanic Yorkshire specimens. Many other species show a 

 greater or less tendency to vary in the same direction, but I 

 think I have given sufficient examples to show that London 

 melanism is not the minus quantity it has been represented. 



I believe almost every instance of London melanism to be 

 what I would call " protective melanism," and not to be classed 

 with the melanism of the North of England and the west coasts 

 of Scotland and Ireland. As an explanation of this latter, I 

 believe JNh". Cockerell's theory, coupling melanism with local 

 huniidit}' and rainfall, to be by far the most reasonable view 

 which has yet been presented to us. 



Eayleigli Villa, Westcombe Park, S.E., August, 1^88. 



DEILEPIIILA GALII IN 1888. 

 Bv John T. Carkingtun, F.L.S. 



Among the more remarkable and least-understood phenomena 

 in the life-histories of insects is the periodical appearance of 

 certain species. Seldom a year passes without its being celebrated 



