MICROPTERYX CALTHELLA. 139 



Bent., "Zoologist," iii., 1086 (1845). Pitsilella, Hb., 341 (1816); (Zell.. "Isis," 

 1839, p. 185). ? Isobasella, Stdgr., " Bed. Ent. Zeits.," 1870, p. 289 ; Hein. and 

 Wocke, " Schmett. Deutsch.," ii., p. 772 (1876). Urticaella, Costa (1836). 



ORIGINAL DESCRIPTION. Phalaena Tinea calthella. Atra, alls 

 superioribus totis aureis, capite ferrugineo. Minuta. Antennae vix 

 corporis Iongitudina3. Alae superiores cerfco situ totae aureae appa- 

 rent : alias atrae. Differt a Ph. frischella antennis basi minime 

 auritis, capite ferrugineo ; corpore quadruple minore. Habitat in 

 floribus Calthae frequens (Linne, Faitna Suecicae, ed. ii., No. 1432 

 p. 367). To this he adds : " Habitat in Calthapalustris floribus " (Sys., 

 Nat., xiith ed., p. 895). 



IMAGO. Fore-wings, 7-9mm. ; unicolorous greenish-golden (and 

 usually with the base from the costa to the inner margin purple). 

 Hind-wings bronzy-grey, the apical area tinted with purplish. 



SEXUAL DIMORPHISM. The head of the male is yellowish, of the 

 female, ferruginous. The male is much smaller than the female. 



VARIATION. Zeller describes (Linn. Ent., v., p. 323) two forms of 

 the species : 



a. Capillis ferrugineis, alls anterioribus virescenti-aureis (post mortem sul- 

 catis), basi purpurea. 



b. Al. ant. basi vix purpurea, ? . 



It is quite clear that var. /;. is, if both forms be referable to M. 

 calthella, the Linnean type, the latter of which has the fore-wings 

 uniformly golden, and not purple at the base. The common form 

 (ab. a) might, unless this be a purely sexual difference, be called ab. 

 purpumscens. Atmore says that at King's Lynn some specimens have 

 a purplish- brown tint towards the apex of the wings. Zeller's 

 var. b., which we have suggested, may be the Linnean type ; appears 

 to be the form described by Staudinger, as M. isobasella [Bed. Ent. 

 Zeit., xiv., p. 289 (1870) ; Hein., ii., p. 772 (1876)] . This is directly 

 referred to by Snellen as calthella var. isobasella \_Vlind., ii., p. 1065 

 (1882)] , but if it be really this species, then M. isobasella, Stdgr. is a 

 synonym of calthella, Linn., and the purple-based form (erroneously con- 

 sidered by Staudinger as the type) will be called ab. purpurasccns, n. ab. 

 Considering the uncertainty existing as to the specific distinctness of 

 isobasella, it may be well to quote the description of Staudinger, who 

 writes as follows : " 69. Micropteryx isobasella, n. sp. (? caWiella\&r. b, 

 Zell., Linn. Ent., v., p. 823). I took a pair of this insect last year on 

 July 8th, on flowering bushes, in the evening, at Macugnaga, among 

 numbers of M. aruncella, which was there common. The two speci- 

 mens, nearly 10 mm. in expanse, are accordingly but little larger than 

 calthella, and perhaps only a local form thereof. Since they have 

 entirely unicolorous, shining green fore-wings, without the trace of a 

 violet base, they agree in so far with the var. b described by Zeller 

 (I. c.). On the other hand, their hind-wings are very strongly violet- 

 coloured, much more strongly than any German calthella. Moreover, 

 the fringes of the fore-wings at their base, especially in the female, 

 have a very beautiful violet-purple gloss which does not occur in 

 calthella. The rust-yellow hairs of the head, length of antennae and 

 the thorax are as in calthella, but the small shoulder covers (epaulettes) 

 are scarcely tinged with violet. Whether we have to do here with a 

 species or a local form of calthella, can only be established by a large 

 number of examples from various localities" [Berl. Ent. Zeit., xiv., 

 289 (1870)] . Durrant inclines to the opinion that isobasella is distinct. 



