)08 THfe CANADIAN ENTOMOLOGlSt. 



makes with the costa not being equal, but slightly obtuse inwardly and 

 slightly acute outwardly, and it also curves a little outwardly, and if pro- 

 duced would strike the outer margin about i/6th of the distance between 

 the apex and inner angle forward of the latter i)oint, while in Thalictri it 

 is almost invariably exactly at right angles with the costa, is generally 

 broader in pro])ortion to length, and if produced would exactly strike the 



inner angle. 



In Grote's description of Cerussata there appears to be a curious 

 error, as in describing the t. p. line he says "regularly dentate between 

 the veins," while the teeth which point outwards are on the veins and the 

 lunules in the interspaces. The apical patch is generally a little brighter 

 ;n Cerussata than in T/ialidri, and the subterminal line differs slightly in 

 the two forms, but from its general obscurity and some tendency *to varia- 

 tion, it is not easy to define the slight diflerences. 



Secondaries : In Thalictri the tendency is to a more dusky hue, 

 though some specimens of Cerussata are as dark, and there is frequently 

 a well-marked exterior line as in Holland's Fig. 15 in Thalictri, but there 

 is great variation in this as well as in the depth of the shade. 



Below the wings are smoky, the primaries darker, with a well-marked 

 median line crossing both wings, the course of it on the fure wings 

 differing slightly from that in Cerussata, as it runs straighler towards the 

 apex, and then turns rather sharply towards the costa. Uiscal marks 

 generally present on all wings. In other points not differing noticeably 

 from Cerussata. 



Had we only the moths, however, I should not Iiave ventured to 

 describe the species, but the great difference in the larva? renders the dis- 

 tinctness of these species absolutely certain. The larva of Cerussata has 

 been well described by Bird, Can. Ent., XXXII, 232, and the following 

 is a description of that of Thalictri, taken nth Sept , 1904 : 



Lenglli in motion 15 lines, at rest 14 lines. Head rather small, 

 smooth and shining, chestnut brown, mouth-parts darker, cervical shield 

 as wide as head, covering most of ist thoracic segment, slightly yellower 

 brown than the head, narrowly edged at sides with darker brown. Body 

 cream colour, with a transverse pinkish shade in the centre of each seg- 

 ment. No longitudinal stripes. Warts small to minute and incon- 

 spicuous. Anal plate small, almost smooth, shining, same colour as 

 cervical shield, slightly edged above with darker brown. The two rear 

 warts on the upper part of the anal segment are slightly united into a 



