198 [February, 



speaks of one out of Salvage's seven specimens having the basal portion 

 decidedly paler, that is, I may take it, one only out of twenty-four, 

 and of the others as variable in depth of tint ; but I do not think 

 Mr. Barrett will venture to deny that the darkest hind-winged $ of 

 the southern form is over its whole surface, and especially in its basal 

 portion, lighter than the lightest specimen of the northern. In con- 

 nection with this point, I wish to draw attention to a fact I had not 

 noticed before. If the pale lilac-grey streaks of turionella be examined 

 through a glass, they will be found finely freckled with minute darker 

 points, which, while they tone down the pale streaks, never interfere 

 with their distinctness, or make it difficult to distinguish between the 

 darker ground colour and the paler transverse markings ; but in the 

 Scotch form the whole basal two-thirds of the fore-wing is thickly 

 sprinkled with irregular dark grey or blackish atoms, which cause the 

 markings to seem to run one into another, and, in fact, give the insect 

 its obscure appearance, and these dots may also be observed in fewer 

 numbers in the rusty apical third. Nor are they confined to the fore- 

 wings, it is to this same sprinkling of dark grey atoms that the 

 hind-wings owe their dulness ; whereas, in turionella ? , though the 

 hind-wings are always darker than in the $, the dark scaling is con- 

 fined to the marginal areas, the basal portion merely appearing more 

 opaque, without actually possessing any dark scales. 



Over and above all these differences, the fringe of the hind-wings, 

 except just at the apex, is in turionella, both $ and ? , always white, 

 never in the Scotch form. Mr. Barrett says whitish ; compared with 

 turionella they are grey. 



Now for Mr. Barrett's conclusion. He goes on to say, "the only 

 distinctions which Mr. Warren specifies for posticana are ' the smaller 

 size ' and ' the colour of the hind-wing ;' but as I (Mr. B.) have 

 shown, southern turionella vary down to the same size, and there is no 

 constancy in the colour of their hind-wings." Mr. Barrett has not 

 shown either : out of twelve bred turionella, he has one nearly as small 

 as posticana, one intermediate, ten of the full average size ; and I affirm 

 that the lightest hind-winged specimen of the northern-form is always 

 darker than the darkest $ of the southern, and never has white fringes 

 to the hind-wings, which turionella always has. 



Finally, of the two difficulties which my friend Mr. Barrett finds 

 facing him, I can only say, that I hope to keep up the reputation in 

 which he is pleased to find the first ; and of the second I will ma"ke 

 him a present, for Mr. Salvage's belief may be wrong, and, if right, 

 proves nothing — a full-fed larva, accidentally ejected from its home in 



