ON THE VARIATION OF HYDROECIA CRINANENSIS. 81 



with the other members of the group — to which H. crinanensis (so far 

 as British species, and so far as appearance goes) belongs. 



The first fact to notice is its extreme inchnation to form local 

 races. Of the sixteen original specimens, brought from the Crinan 

 Canal locality by Messrs. iJacot and Simes in 1899 — which survive, 

 or have reached my hands, all are light. The three specimens from 

 the Maddison Collection, labelled " Inveran," are light. Mr. J. E. 

 R. Allen's single Bolton (Lanes.) and Enniskillen specimens are 

 light. On the other hand, of the 23 specimens which Messrs. P. A. 

 and D. A. J. Buxton captured at Liddlebank and neighbourhood in 

 the autumn of 1909, only one or two are light, the rest dark, some 

 almost melanic. Of the seven which Mr. Le Marchant captured at 

 Aberfeldy in 1909, two are quite melanic, while the rest are light. 

 With colour, goes size, the light specimens being appreciably larger 

 than the dark. 



There appears to be no particular relation between the localities 

 and the variation in colour. The light form coming from the extreme 

 north of Scotland and from the Crinan Canal, the dark from Aberfeldy, 

 at a considerable elevation, and from the Liddlebank. 



All these localities are, as far as I have been able to find out, in the 

 neighbourhood of running waters, as opposed to the mosses and bogs 

 of H. lucens, the salt-marshes of H. paladis, and the general habitats 

 of //. nutitans. I have been unable to detect any trace of sexual 

 variation. As to the type form of the insect, there exists the difficulty, 

 that the species was named from its genitalia characters and not from 

 the wing-colour or markings. Two specimens, given to me by Mr. 

 Bacot, were the first detected. These two specimens, males, are un- 

 fortunately of difterent forms, so I suppose I shall be compelled to take 

 the first examined as the type, and as such I describe it. 



Light Forms. 



1. Pale yellowish-grey, yellow reniform stigmata =ab. pallida-flavo, n. ab. 



2. Bright brick-red, with darker central area reniform 



and orbicular stigmata orange =ab. crinanensis, B. and P. 



3. Dull red, dull orange reniform stigmata =ab. riifescens-flavo, n. ab. 



4. Dull red, white reniform stigmata =ab. rufescens-albo, n. ab. 



5. Gi'ey-red, yellow reniform stigmata (to which the 



second type specimen belongs) =ab. grisescens-Jlavo, n. ab. 



6. Grey-red, white reniform stigmata =ab. grisescens-albo, n. ab. 



Dark Forms. 



7. Dark chestnut-brown, yellow reniform stigmata =ab. castanea-Jlavo, n. ab. 



8. Dark chestnut-brown, white reniform stigmata =ab. casta nea-alho, n. ab. 



9. Pied-black, white reniform stigmata =ab. nigrescens-albo, n. ab. 



The orbicular stigmata are rarely distinctly tilled in with lighter 

 colour. The dark central area appears throughout the pale forms. 



The impossibility of distinguishing this species by the eye has been 

 acknowledged by so many entomologists that the fact must be known by 

 this time. There seems to be a general look about the insects, which 

 differentiate it from H. lucens. The occurrence of the pale central 

 line on the hindwing is not unusual, and is commoner than in H. 

 lucens, H. nictitans, and //. paludis, in all of which it is, however, also 

 found. But the dark specimens of //. crinanensis are much darker 

 than any H. lucens or H. paludis I have ever seen, and, although H. 

 nictitans occasionally occurs very dark, there is happily no difficulty in 

 distinguishing between it and Jl. crinanensis. 



