qo iFebniary, 



adding, " varieties of this are innumerable, and they cannot all be described in words ; 

 the ground-colour in many is very vehite, in still more whitish-grey, in others 

 ashy-grey, and in many brownish-grey ; in the last two forms the markings are the 

 least distinct ; the markings differ in colour — brown, blackish, rust-colour or reddish. 

 This species is more variable than any other Geometra known to me." 



Esper's figures of biundularia,-v/h.ic;\\ he states to be synonymous with crepuscu- 

 laria, W. V., are far less satisfactory. The male has the wing colouring and 

 markings of the pale form pretty accurately, but its antennae are stout and strongly 

 pectinated — the antennae in fact of Boarmia rhomboidaria — while in the present 

 species the pectinations, though present, are merely rows of minute bristles, and the 

 antennae are slender and weak. His female figure is one upon which no one I think 

 would like to pronounce. In the text he says that the " ground-colour is very pale 

 ashy-grey, sometimes darkened by thickly sprinkled blackisli atoms ; the fore-wings 

 have three scolloped transverse lines at even distances, the first edged throughout 

 with a yellowish-brown border, which is sometimes obsolete or very pale; in the 

 middle band, especially in the female, is sometimes a blackish spot accompanied by 

 two white dots, but these are often absent; sometimes the two last bands are con- 

 nected together by an intermediate transverse stripe. The hind-wings also have 

 three waved black bands, but they are much more slender, and the middle one only 

 bordered with brownish or yellowish, sometimes in the form of a band. Under-side 

 similar but more obscure, and dusted with blackish. Varying in depth of markings 

 and in ground-colour to brown or yellowish. Larva varying much, according to tlie 

 food plant- -brownish-green, brownish-grey, or partly greyish and partly pale green." 



De Geer's figure is very little dusted, so probably is intended for the pale 

 form, but that is merely a matter of conjecture. He calls it "the dirty-white moth," 

 and says that it is " dirty-white clouded with grey and with dark lines." De 

 Villers furnished it with a name — hiundiilaria. 



Hiibner's figure 158 is our pale June form. He calls it crepuscularia. It is 

 also the crepuscularia of the Vienna Catalogue, and biundularia is quoted as a 

 synonym ; but then the authors say that crepuscularia <J has strongly pectinated 

 antennae and feeds on Aquilegia vulgaris ! also that the only question as to the 

 identity of crepuscularia and biundularia consists in the presence or absence of 

 marginal spots. Since all the forms possess the marginal spots, this does not help 

 us much ; but so do the figures, and I am driven to the conclusion that the spots 

 referred to are the pair in the submarginal band, which often are obscured in a 

 brown cloud or hidden by grey or blackish colouring, or even obsolete. 



I really think that the only point which emerges at all clearly from all this is, 

 that the authors quoted regarded all the forms as constituting one species, figuring 

 the white forms, describing them and the grey, but comparatively ignoring the brown 

 as a variation : but this is not the point of present contention. Our own authors, 

 Haworth, Stephens, &c., regarded the species as distinct, and they called the more 

 ferruginous or browner form, or species, abietaria. When the name ahietaria was 

 shifted to the species called by them sericearia, Mr. Doubleday seems to have adopted 

 laricaria for the browner insect. When that was given up he seems very naturally 

 to have adopted crepuscularia for it, seeing that biundularia was clearly first de- 

 scribed as the whiter insect. I have followed him, I confess, in my paper, rather as 

 a matter of habit than of serious opinion, since they seem to me to be merely 

 varietal names, but I am now inclined to tliink biundularia the proper name for the 

 whole of the forms — as one si)ecies. — C. G. B.]. 



