1909.] 



Two Races of the Moth Acidalia virgularia. 



145 



batch yielded 16 specimens, hardly variable, intermediate to light-inter- 

 mediate, weakly lined for the most part. From the former of these batches 

 sprang, as Fi , a brood of 17 specimens, rather constant, with a uniform facies 

 which struck one as recognisable even when they were emerging ; all are 

 intermediate in colour, the dusting weak, the lines rather strong. 



Brood I. — Obtained but not carried on. The single family (F 8 ) consists of 

 46 specimens, intermediate, decidedly constant. 



Brood i. — Continued to generation F ao . F 8 consists of 22 specimens, 

 rather constant, normal intermediates. F 9 was obtained in duplicate ; from 

 one pair (labelled i 0) resulted a very variable brood of 32 specimens : 

 5 or 6 pure light, others near, 7 or 8 pure dark (some quite extreme), others 

 near, and various intergrades ; from the other pair (labelled i <C>) another 

 variable brood, of 12 specimens only, mostly lightish-intermediate, 1 almost 

 pure light, though slightly brown tinged, 1 pure dark, 2 darkish. F 10 was 

 reared from both these broods ; that from the former consisted of 44 

 specimens, intermediate to dark, presumably from some of the darker 

 examples among the parent stock ; the latter of 25 specimens, varying in 

 colour from white to intermediate, yet with a most conspicuously definite 

 facies, all being well lined, with the central shade strong and clear cut in 

 addition. 



Brood J. — F 9 , 29 specimens, intermediate to lightish-intermediate, fairly 

 constant. Fi , 5 only, certainly variable, though without extremes — 

 altogether too few for generalisations. The reciprocal cross (j) was not 

 secured. 



Brood K. — Obtained in duplicate. Both batches (56 and 38 specimens 

 respectively) normal intermediates, the variation slight. Some undersized 

 specimens look a little pale, but this is because of their weak scaling. 



Brood k. — 40 specimens, variation moderate, from light-intermediate 

 to dark-intermediate. 



The cjuadroons and other irregular crosses have next to be briefly dealt 

 with. In the first filial generation pure light $ was crossed with hybrid $ 

 (out of the brood described as A, number (2) in this paper), and the strain 

 carried on for four generations (F 2 to F 6 ). It continued " intermediate," 

 with the variation appreciable but not considerable, only in F 6 there were 

 more of the whiter specimens. In generation F 6 this quadroon race was 

 crossed with the hybrid race called / in this paper ; the variation in the 

 offspring (F 7 ) was only very moderate, ranging from light to lightish- 

 intermediate. 



Also in generation F 6 , crosses of bxc, bxf, and G x G were obtained, but 

 only bxf was followed up to subsequent generations. All these three were 

 VOL. lxxxi. — B. L 



