52 Cross-breeding of Two Races of Acidalia virgularia. 



differences between the two forms, namely, the speckling of virgularia, 

 behaves in most cases as a Mendelian dominant to the absence of this 

 speckling in canteneraria. Even to this rule I am bound to admit there 

 are certain exceptions. To account for this I have to assume that, whilst 

 the heterozygote is usually more or less like virgularia, it may sometimes 

 be indistinguishable from canteneraria. 



The other difference between the species and its variety is that virgularia 

 is often, and in the London form always, much browner or yellower in 

 ground-colour than canteneraria. Of the various colours of ground seen in 

 the hybrid race I have been able to suggest no explanation, though, as 

 already noted, a certain amount of order is discernible, especially in the 

 fact that the males are almost invariably darker than the females. 



In regard to size it has been shown that, taken as a whole, the individuals 

 fall into a normal curve of error, but that some of the broods show con- 

 siderable departures from the normal, for which no explanation in heredity 

 or environment is forthcoming. 



It should be mentioned also that both speckled and non-speckled, yellow 

 and white individuals occurred in broods which hibernated as larvae as well 

 as in broods which passed through their whole development in a couple of 

 months in the summer, so that these differences are not likely to be due to 

 environment, nor are they seasonal forms. 



The specimens have been placed, with Messrs. Prout and Bacot's material, 

 in the Hope Department of the Oxford Museum. 



