VARIETIES OP NOCTU^ IN THE BRITISH ISLANDS. 229 



same month, and each has its two broods, with three weeks' 

 interval between each. Thus we get — 



June, July. 



Istweek. 2d week. 3rd week. 4th week. 1st week. 2d week. 3rd week. 4th week. 



A... ^^2^2 ? — — — ^ &C 



B... — — — <? <y?(?? ? — &C. 



From this it is readily seen that we have males of b flying 

 with females of a during the last week of June, each without its 

 proper mate, while again, at the end of July, some late females 

 of B might be found with early males of the second brood of a. 

 What circumstances could be more favourable for the production 

 of hybrids ? I have no knowledge whether this is actually the 

 case with any of the species of Lyccsna that have been under 

 discussion, but I wish to show that, on general grounds, the fact 

 of two butterflies overlapping in their periods of emergence is 

 more favourable for hybridization than if they flew quite 



synchronously. 



(To be conoluded.) 



Correction. — Maynard's reference (p. 5) to black females of L. pseud- 

 aryioliis probably origiuated in the original error of referring the black 

 males to the female sex. There is no satisfactory evidence of a black female 

 of pseudargiolus. 



CONTRIBUTIONS TOWARDS A LIST OF THE VARIETIES 

 OF NOCTU^ OCCURRING IN THE BRITISH ISLANDS. 

 By J. W. TuTT, F.E.S. 

 (Continued from p. 210.) 

 Mamestra, Och., sordida, Bork. 

 The type of this species is thus described in Borkhausen's 

 * Naturegeschichte der Europaischen Schmetterlinge,' p. 239 : — 

 " It is as large and nearly the shape of Noctua hrassiccg. The 

 fore wings mottled, with a mixture of earth-grey and pale dirty 

 brown; markings extremely indistinct and pale. In some specimens 

 three pale transverse lines can be distinguished : the one at the 

 base is very pale ; the second has particularly strong zigzag marks 

 near the inner margin ; the third forms a slight semicircle. 

 They are all paler than the ground colour, but edged with darker. 

 On the inner side of the third line is a row of brownish moon- 

 shaped spots, which turn their hollow sides inwards. Close to the 

 hind margin is a pale zigzag line, which forms in the middle a 

 small Latin W- The ordinary markings between the second and 

 third transverse lines are very faintly marked ; the claviform is 

 indistinctly surrounded with whitish grey, and scarcely visible ; 



