1909.] Two Races of the Moth Acidalia virgularia. 141 



former of the two F 4 broods, 32 specimens varied little, though not absolutely 

 inappreciably, all light, yet not quite so pure as the original Hyeres strain. 



Brood b. — Obtained in duplicate, one strain carried on to generation F 5 , 

 the other to Fi . 



(1) An interesting strain on account of an apparently hereditary pre- 

 dominance of the female sex, figures therefore given in full. In F 2 

 (28 S, 36 ?) all were intermediates, though somewhat more variable than 

 most first crosses. F 3 was duplicated ; one brood (13 c?, 17 ? ) showed 

 considerable variation, ranging, in both sexes, from pure dark, through 

 intermediates, to nearly, but not quite, pure light ; the other brood 

 (13 , 24 $ ) also varied rather considerably : 3 almost pure dark, a few 

 others approaching these, others intermediate or lightish, 7 with a 

 characteristic facies, almost of the pale, well-lined Hyeres form, yet less 

 extreme and less white. F 4 , from the former of the F 3 broods, consisted of 

 14 $ , 25 $ : both sexes quite variable, several <$'s dark, 1 or 2 ? 's light (not 

 strongly lined), the $ 's thus averaging somewhat the lighter. In F 5 

 (17 J 1 , 27 ? ) the range of variation was much as in F 4 . Adding the above 

 numbers together, we find that this strain yielded only 85 $ against 129 $ , 

 a proportion of 2:3. 



(2) This proved on the whole a very stable strain, though generations F 4 

 to F 6 varied more. F 2 was very uniform, intermediate. F 3 (7 only) similar, 

 may have been a shade darker and a few showed a dark border, which 

 became a feature of the strain. F 4 distinctly variable, though not quite 

 reaching either extreme ; a dark central shade, quite a feature of some, 

 lacking in others. F 5 (19 only) very similar to F 4 , but smaller, and perhaps 

 hardly so variable. F 6 (66) strongly variable, particularly in the expression 

 or suppression of the two rows of transverse dots, there being a sudden 

 outcrop of specimens in which they are very pronounced — none such being- 

 observable in F 2 to F 5 . Where these dots are on a white ground 

 (14 specimens), " pure light " is produced ; the rest are intermediate to dark, 

 none very dark. F 7 consisted of 3 only, intermediate, weakly marked, but 

 2 with the borders darkened. F 8 , 23 specimens, a singularly uniform brood, 

 a phase of "intermediate" without strong dusting or Hues of dots, the distal 

 margin often darker. F 9 was duplicated, but both the broods (46 and 

 11 specimens respectively) closely followed F 8 , though a few in the larger 

 brood were a little more heavily dusted. Fi was almost a failure, only one 

 (intermediate) specimen coming through. 



Brood C. — Continued to generation F 9 . In F 3 there were only 3 poor 

 specimens, apparently intermediate, but no exact analysis possible. F 4 , 

 a large batch, moderately variable, range from almost pure light to darkish 



