1909.] Two Races of the Moth Acidalia virgularia. 135 



apparent Mendelian dominance in the typical form of Callimorpha clominula 

 over its yellow-hindwinged aberration rossica, and of Abraxas grossulariata 

 over the aberration varleyata. He has very obligingly furnished us with 

 statistics, so far as the experiments have yet gone ; and as they are hitherto 

 unpublished, we take this opportunity of putting them on record. Of 

 C. dominula, a type $ x rossica $ paired in 1906 produced in 1907 a brood 

 consisting entirely of typical specimens ; a pair of these gave in 1908 the 

 following result: 34 typical, 10 ab. rossica — there was a great mortality 

 among the larva? before and during hibernation, fully 60 per cent, dying. 

 Of Abraxas grossulariata, a type $ x varleyata ? paired in 1907, produced 

 in June-July, 1908, a brood consisting entirely of typical specimens ; 

 pairings from these gave, as a partial second brood, October-November, 

 1908, 24 of the type (including one aberrant but not varleyata) and 7 ab. 

 varleyata — the rest of the larvae now hibernating. 



After some consultation we decided upon the small geometrid moth known 

 as Acidalia (or Ptychopoda) virgularia, Hub., as meeting the essential condi- 

 tions. There are, be it observed, practical difficulties to be encountered with 

 many species, which have been overlooked by theorisers on the nature of the 

 work that ought to be done by Lepidopterists. Thus many moths are 

 exceedingly difficult to pair in confinement ; many are extremely averse to 

 inbreeding, so that an inbred strain cannot be continued beyond two or 

 three generations ; many are difficult to bring through the winter, or require 

 food-plants which are not always obtainable. 



Convenience in Hearing. — Acidalia virgularia, on the other hand, will feed, 

 apparently, on almost anything belonging to the vegetable kingdom, leaves 

 of all sorts — whether fresh or withered — sliced carrot, etc., proving equally 

 acceptable to it; it pairs very readily, is continuously-brooded throughout 

 the summer, feeds up rapidly and generally without need of hibernation, 

 and does not deteriorate through continuous inbreeding ; moreover, its 

 small size is a practical convenience both for the accommodation of large 

 numbers of larvse in a small space and for bringing large numbers of the set 

 moths under the eye at the same time. Few, if any, other British species 

 would offer all these advantages to the same degree ; and as Acidalia 

 virgularia produces in the south of France a race so different-looking from 

 the British that more than one British field naturalist on seeing it has failed 

 to recognise even the species, it is not difficult to trace the influence of the 

 respective parent strains in crossings. 



Origin of Stock. — Ova and pupa? of the southern French form were kindly 

 supplied by Mr. H. Powell, F.E.S., from Hyeres ; wild moths of the London 



