44 



CidaricB, C. russafa and C. immaiiata. The variation is, I think, 

 greatest in the former species. 



Cidaria russata has the broad central bar of the upper wings 

 either black, broT\Ti, red, or gray, and in some cases nearly white. 

 Specimens are occasionally found suflFased almost entirely with 

 black, and the relative proportions of the colors varies con- 

 siderably. It would be impossible to say what is the normal 

 color in this species. I find that in the outer Hebrides and in 

 the island of Arran that the coloration is much more uniform, the 

 general appearance of all the specimens being grayish. 



Cidaria immanata varies in a similar manner, except that 

 only in the Shetlandic specimens have I seen any tendency to red 

 in the centre of the wing. 



Peronea cristana varies from almost black to nearly white, 

 and the tufts in the wings vary in color from black, red, yellow, 

 or white. The same difference also obtains in the shoulder mark- 

 ings and in the dashes on the inner edges of the wings. Several 

 others of the Peronea differ in an equally remarkable manner 

 amongst themselves, whilst one species, on the other hand, is 

 very constant in color in this country. 



Topomorphism. — I place under this class all local variations. 

 These may be sufficiently constant as to admit of being considered 

 subspecific or racial; and in certain districts the variation appears 

 to take place in response to the geological environment. In the 

 Bdtish Isles the most remarkable topomorphic variation is that 

 of Hepialus hiinmli. This species which, so far as I am aware 

 of, in England and Scotland has a silvery colored male, and a buff 

 female with a few reddish markings; but in the Shetland Isles 

 it appears to be subject to many variations, the coloring of 

 the sexes being reversed both in the case of males and females; 

 and some varieties being more melanic, so that the ffepialus 

 humuli of those islands has been raised to a subspecific rank, 

 HethJandica by Staudinger, and as well as being topomorphic is 

 also truly polymorphic. In the Outer Hebrides Boarmia repan- 

 daria departs from the normal coloration of that species as found 

 in England, viz., various shades of brown, to a prevaihng slaty 

 gray, with darker markings. To this well-defined topomorphic 

 variation I have ventured to give the name of Sodm-ensivm. As 

 an instance of a topomorphic variety dependent apparently on the 



