98 



THE ENTOMOLOGIST. 



of the forms are distinct, and without, so far as I am aware^ 

 intermediates being known, there are others which grade into 

 each other in a remarkable way, so that it is often impossible to 

 say with which of two forms a particular specimen should be 

 placed. This of course adds very greatly to the difficulty of 

 tabulating the variation. 



The forms divide themselves into two divisions, so distinct 

 that if the earlier stages were not known, one would at once 

 follow the example of the lepidopterists of a hundred years ago^ 

 and class them as distinct species. 



The first of these divisions comprises those handsome and 

 striking forms which are known popularly as "streaks" — that 

 is to say, those with a longitudinal black streak on the superiors. 

 This division includes the type revayana, Scop., and abs. ramosana,. 

 Hiib., and stoninus, Curtis. 



The second division, which comprises the great bulk of the 

 known forms, has certain peculiarities which pertain to all 

 of them to a greater or less degree. The most prominent and 

 important of these is unquestionably a large blotch on the costal 

 region of the superiors; this blotch, which is always darker in 

 colour than the surrounding area, occupies the central costal 

 margin for about one-third of its length ; it extends ordinarily 

 in a triangular shape to the centre of the wing, and in this 

 form it is most pronounced in ab. afzeliana, Swederus, or it may 

 continue as a fascia across the wing to the inner margin, as in 

 ab. bifasciana, Donovan. 



Another striking character in this group is a black or red- 

 brown discoidal spot in the centre of the superiors. This is 

 present in the great majority of the forms, but not in every one. 

 A third characteristic is a double series of fuscous spots or 

 blotches, somewhat smaller than the discoidal spot, which cross 

 the superiors transversely ; one of these is about one-third of 

 the length of the wing from the base, and the other is near the 

 hind margin. Most of the forms have also two or more dark 

 fuscous lines which cross the superiors transversely. 



For convenience of classification and arrangement I subdivide 

 this division into four groups, Avhich I call respectively the 

 dilutana, Hiib., afzeliana, Swederus, undidana, Hiib., and degene- 

 rana, Hiib. groups. In the case of each of the forms that have 

 been already described I give the original description, with, in 

 one or two cases, the English translation. 



S. revayana is in Britain a widely-distributed species, occurring 

 throughout as far north as Boss ; it is found also in Ireland. 

 By far the greater number of specimens in our collections hail, 

 however, from the New Forest, where the species is usually 

 somewhat abundant. In this district it is, moreover, more 

 variable than in many others, in which the duller-coloured 

 forms alone are to be found. 



