THE YOUNG NATURALIST. 



213 



hetularia {Boulledayarid) are by no means rare, and are easily reared. 

 But though I have bred a goodly number of it, all that ever I obtained were 

 either one form or the other, either true Betularia, or true Douhledayaria. 

 Intermediate forms of this species do, however, exist, but they are so rare 

 that I never took but one, and never saw but two. I noticed a singular 

 thing when breeding this species. From ova, deposited by a black female I 

 reared a considerable number of imagines, of which about one-half were black, 

 and the other of the type. I then tried to pair two black ones, but they 

 took no notice of each other, though both paired readily with a grey specimen 

 of the opposite sex. Mr. Malings of Newcastle, who supplied me with the 

 ova, told me his experience in this particular was the same as mine. This 

 certainly does not obtain with all species, but I once bred a buff-coloured 

 female grossulariata that would not pair with any male I could obtain. 



Rurea var. combust a is similar in character to the last. The darker 

 marking of the type have spread over the whole of the superior wings. The 

 type varies very slightly in the extent of the dark markings, but I never saw 

 one approaching Combusta. The banded forms of Boarmia repandata, and 

 Acidalia aversata, are also varieties similar in character to each other. The 

 dark scales in each being gathered together in a band across the wing. 

 Neither is rare, but I never saw an intermediate form of either. I might 

 multiply such illustrations ad nauseum without going beyond our British 

 fauna, but it is unnecessary. I have given enough to show that where two 

 or more well marked forms of a species exist, whether sexual or not, that 

 both or all, continue to be produced without examples intermediate between 

 them, or if intermediates occur, they are so rare that they can only be con- 

 sidered aberrations. In species that do not produce well marked forms 

 this peculiarity does not obtain, It would almost appear that those which vary 

 excessively are unable to produce a distinct variety. 



Now this permanence of both type and variety, where both occur together, 

 is very curious. Still more strange is the permanence of the various sexual 

 forms. If a negro married a white woman their children would be mulatto, 

 intermediate between the two. This, however, does not obtain with 

 A. mendica. The sooty hued male and white female do not produce a 

 mulatto-like offspring, but all the males are dark like the father, and all the 

 females pale like the mother. If this negro's brother were wedded to a 

 yellow-skinned Asiatic, how amazed we would be to see their boys black, and 

 their girls yellow, and how earnestly we would declare it to be impossible, 

 should these mothers have daughters, some of whom resembled themselves, 

 and some their sister-in-law. Yet this is exactly what occurs with dimorphic 

 species, like Papilio turnus, and others that have been named above. 



