t. BiSTORTATA (cREPUSCULARIa) AND t. CREPUSCULAtllA (biUNDULARIA) . t 



umbreous instead of fulvous character of the brown markings. On 

 June 19th, the Rev. C. Thornewill, of Burton, also took a brown- 

 lined specimen, very similar, and these two are the nearest to 

 the southern crepuacularia that I have seen." This is the sum total 

 of the evidence offered by Mr. Barrett, and the opinion based on this 

 evidence reads as follows : — "It seems to me unreasonable to attempt 

 to keep up the purely artificial distinction between these two forms. 

 They should surely be united." However, like Mr. Smallwood, Mr. 

 Barrett was not comfortable, so he goes on : — " If we admit that these 

 forms constitute but one species, we are still confronted by the remark- 

 able phenomenon, for which no reasonable explanation seems to pre- 

 sent itself, that two races exist in the same localities, emerging at 

 different periods, and presenting a constant difference in the shade of 

 colour.*'* We know that the hiumlidaria which emerge in May, are 

 not the offspring of the April crepmcularia,-\ and, as far as investiga- 

 tion has gone, we find that the offspring of each form emerges at the 

 same time as its parents, and presents the same characteristics' — 

 setting aside the few which feed up quickly and emerge the same 

 season, and exhibit similar characters in a modified form. We have, 

 in fact, a curious instance of dimorphism in both sexes "| (Ibid., p. 87). 

 Now, if this remarkable paragraph means anything, it appears to me 

 to mean this— I see there are two very distinct species of moths 

 which I can readily differentiate, but as I am puzzled where to put a 

 few German specimens, and a couple of Midland ones, it will save a 

 lot of trouble to call them one species. 



Mr. Robson very fairly criticised (E.M.^f., xxiii., pp. 111-112) this 

 paper. He adds no new fact, however, to the discussion, and we demur 

 strongly against his acceptance of the statement, that " the offspring 

 of both insects in favourable seasons or localities feed up and emerge 

 the same year, or part of the brood does." We doubt whether more 

 than a very occasional specimen of biundularia does this. It has 

 certainly never been shown, except in two solitary instances, that it 

 does so. His conclusion that " it seems much more unreasonable to 

 ignore the truly natural distinction between them, merely because, in 

 odd specimens, we are unable to find an artificial — perhaps I had 

 better say superficial — distinction," will surely commend itself to all 

 lepidopterists. 



The next occasion on which Mr. Barrett refers to this subject in 

 the magazines is in 1895, when he describes (E.M.M., xxxi., p. 199) 

 some observations made by Sir John T. D. Llewelyn on the increase 

 of melanism which was observed in " Tephrosia crepuscularia, and its 

 form, biwidularia." It would appear that, in 1866, Sir J. T. D. 

 Llewelyn first observed the dark aberrations of T. crejmscularia. He 

 reared the same form from eggs laid by dark females in 1868 and 

 1872, and it was not until "ten years later that the same careful 

 observer found that this form of variation had extended to the parallel, 

 later-emerging, whitish form of the species (by some held to be 

 distinct) biwidularia ; but he noticed that in this the variety was 

 ' black, but with the sub-terminal line conspicuously pencilled out in 



* This is remarkable, in face of the importance attached to the colour of 

 the Staffordshire specimens in the paragraph numbered 4 {ante, p. 6). 



t Compare this with the remarks quoted from the E. M. M., vol. xxxii., p. 229, 

 further on in this paper {vide, p. 8). t ? " species," not " sexes." 



