VARIATION AND LOCALITY 137 



to these there is a black form in the North of England which 

 seems to be spreading. In Huddersfield the black was first 

 recorded in 1888, and in 1900 20-25 P er cent, were black. At 

 Rotherham the black or very dark are now prevalent and have 

 increased in the last 15 years. From the Midlands, East Anglia 

 and Southern Counties the returns show only the light and 

 medium forms. 



Of Odontoptera bidentata several intergrading dark forms exist, 

 and these are found exclusively in the North and the Midlands. 

 Unicolorous blacks have been found recently in the Lancashire 

 mosses and at Wakefield. At Huddersfield 50 years ago the 

 light forms were prevalent, but now a rather dark brown, not 

 infrequently suffused with black, is the commonest. In Southern 

 Counties only light forms are known. 



Phigalia pilosaria in South England is always light, but in 

 the North the prevalent form is darker. About 35 years ago 

 a form with unicolorous sooty fore-wings and dull grey hind 

 wings was first seen in Yorkshire and a similar form is now taken 

 regularly in South Wales. 



In the following cases the dark varieties were found originally 

 only in the South. 



Boarmia rhomboidaria gave rise about 40 years ago to a uni- 

 colorous smoky variety called perfttmaria. This was at first 

 peculiar to the London district, but it has since been taken in 

 Birmingham and other large cities. More lately coal-black 

 specimens have been found at Norwich, and others similar but 

 hardly so dark were taken in the South of Scotland and at 

 Cannock Chase. 



Eupithecia rectangulata is a similar case. Formerly the 

 light forms were prevalent but within sixty years they have 

 almost entirely been replaced in the South of London by a nearly 

 black form. 



Tephrosia (Boarmia) consortaria and Tephrosia consonaria are 

 exceptionally interesting, for they have both given off dark 

 forms in the same wood near Maidstone, which is far from the 

 usual "centres of melanism." They were discovered in this 

 locality by Mr. E. Goodwin. That of consortaria is a dark 



