THE GENUS OPOKABIA. 815 



The Genus Oporabia. 



(Concluded from p. 286). 

 By LOUIS B. PEOUT, F.E.S. 



2a. — Var. (?) (autumnaria, Weav. =) addendaria, B. -White. — 

 Weaver (Z()(di)iiist, 1852, p. 3495) says that this is readily distinguished 

 from nchnlata and his nef/lcctata [i.e., large nchulata) by the glossy 

 silver and fineness of the wings, and the slenderness of the antennae ; 

 that it varies in size and in shade, some specimens being rather 

 darker, but not M^ithout markings ; and that it rests on branches of 

 birch. He obtained a few in Perthshire in 1851, and very sparingly 

 in previous seasons. He indicates nothing but its larger size, and its 

 attachment to birch, to distinguish it from appro.vwiaria and fili(/ram- 

 iiiaria. As regards the feeding on birch, Mr. W. Salvage says he 

 meets Avith nebidata ( dilutata) onhj on birch, and that the larvae most 

 certainly feed on that tree. Mr. Logan [ZooL, 1858, p. 6285) bred 

 autumnaria (i.e., addendaria) from birch, " the larvte differing sufficiently 

 from that of the common dilutata, but not," he suspected, " equally 

 from that oi fili(irammaria, which had been reared the same season, by 

 a Mr. Wilson, from larvae on heath." Unfortunately, Mr. Logan 

 does not describe the larva ; nor does Mr. Gregson, who records that 

 Greening bred a series from oak ; and also that he himself bred a 

 series of apjiroxiiaaria from birch. Evidently nothing definite can be 

 gathered from the food-plants. 



Mr. C. Fenn tells me that in June, 1875, he received, among a lot 

 of larvfB from Rannoch, a few of an Oporabia, feeding on sallow, 

 Vacciniuin, etc., which Mr. Carrington considered autiuiinaria. He 

 reared them, and the moths emerged at intervals from September 12th 

 to the end of October ; except that they were a little more silky in 

 appearance, they seemed to him, " true dilutata.''' In case, however, 

 they were veritable addendaria, I quote the larval description, which 

 he has kindly placed in my hands. " 15th .June, 1875. Elongate, 

 slightly attenuated anteriorly. Head rounded, body with a few 

 scattered short hairs. Colour green, with a greyish tinge on the 

 back. Dorsal and sub-dorsal lines, and a faint thread between them, 

 grey. A whitish spiracular band, only distinct on the posterior 

 segments, where it margins the blunt anal flap. This spiracular band 

 is shaded below with darker green than the belly, which is paler than 

 the ground colour. Head pale green, dotted with brown." This 

 description is, in some respects, intermediate between normal nebulata 

 a,nd filii/raiiDiiaria. 



Dr. Buchanan White admits that addendaria is very closely allied 

 to jiliiiramniaria, but considers there is a slight difference in the 

 genitalia — a difference which unfortunately is not confirmed by Mr. 

 Pierce's investigations. Dr. White only examined two specimens of 

 each of these species, and the difference, as shown by his figures, was 

 very slight, and perhaps due to some accident in preparation ; at any 

 rate, Mr. Pierce's numerous examples come between Dr. White's two 

 extremes, and apparently yield nothing of importance for differentia- 

 tion. It may, however, be useful for reference if I quote Dr. White's 

 statements : "On the ventral hind margin of the last abdominal 

 segment of a male ( f/mrabia are two short spine-like processes. In 

 dilutata these are rather near each other, and form short spines iongi- 



