1909.] 



Two Races of the Moth Acidalia virgularia. 



147 



Brood D — This aberrant stock in F 6 , which we called D % vi, con- 

 sisted of 41 specimens, 18 of them pure light, 2 nearly pure but browner in 

 ground-colour, a few normal intermediates, and about 12 typical dark. By 

 analogy with the rest of our material this would suggest being a second 

 generation from a hybrid. On account of the riddle of its origin, 5 pairings 

 from this brood were obtained, 2 others attempted proving infertile. 



(1) From a light pair sprang, in F 7 , a brood of 16 (labelled D^vii (2)) all 

 light, about half being quite extreme, the rest slightly more dusted. 



(2) From another light pair, F 7 consisted of 47 (labelled D^vii (3)), 

 rather variable from pure Hyeres form (4 or 5) to intermediates. Their 

 progeny in F 8 (64 in all, from different pairings) varied conspicuously, the 

 majority light to intermediate, perhaps only one really dark, and that not 

 very extreme. In F 9 (two broods, 67 specimens) the variation was less, only 

 ranging from light to intermediate ; all the four actual parents were more or 

 less light. In F w (three broods, 96 specimens) the variation again increased 

 somewhat, but with the lighter forms still in the ascendant and thoroughly 

 dark ones only occurring, and sparingly, in one of the three broods — labelled 

 Dx(l) O, and noteworthy for its darker average tone than its parent brood. 



(3) From yet another light pair, F 7 (26 specimens, labelled D % vii (4)) 

 bred absolutely true to the extreme parent form (= wild Hyeres type). 

 One pairing produced, in F 8 , a further brood of 24, all equally pure, 

 unfortunately lost here. Another pairing produced, in F 8 , a very variable 

 brood of 45 — 15 pure light, about 15 others lightish to light-intermediate, 

 the rest darker, 1 or 2 practically " dark." From a pairing of rather light, 

 well-marked specimens in the latter of these (the variable) was obtained, in 

 F 9 , a brood of 38 varying much less than the parental one, indeed pretty 

 constant light-intermediate, rather well-lined. Their offspring (F 10 , 

 42 specimens) would nearly all be classed as " light-intermediate " in some 

 sense, yet wonderfully variable within this limit ; whitish weak-marked, 

 similar examples but greyer behind the outer line, moderately light strong- 

 marked, intermediate (2 or 3 strongly-marked, 2 or 3 weaker-marked) are all 

 represented. 



(4) From a dark pair, only three specimens were reared in F 7 (labelled 

 1) 3e vii (6) ). These were darkish intermediate. Fortunately a $ and a ? 

 emerged together and copulated. The resultant F 8 (49 specimens) varied 

 a good deal, one only being pure light, the rest about half intermediate 

 (a few light-intermediate) and half darkish to dark, but with intergradations. 

 F 9 (78 specimens, 3 broods) was moderately variable, but all should be 

 classed as broadly " intermediates." Fi (49 specimens) was variable, ranging 

 from intermediate to dark, the average darker than in F 9 ; perhaps about 



L 2 



