276 BRITISH BUTTERFLIES. 



indebted to Bethune-Baker for the following diagnosis (betulae being 

 taken as the type) : 



Face broadish, very hairy, vertex hairy, antennas fixed about the edge of the 

 vertex, fairly widely apart, terminating in a gradually tapered club. Eyes hairy, 

 not large. Palpi porrect, not long, scaled, 2nd segment fringed with hair below. 

 Legs stout, shortish, scaled throughout ; femora fringed closely with hair below. 

 Forelegs with tarsi aborted into a single hook ; hind tibia with one pair of short 

 spurs. Wings : Primaries broad, nearly three-quarters of their length, costa 

 slightly and evenly arched, termen nearly straight, inner margin very slightly 

 excised in centre. Secondaries with termen slightly truncate (not excised) between 

 the veins, except between veins 1 and 2, and 2 and 3, which are deeply excised to 

 form the tail, lobe fairly developed. Neuration : Primaries with vein 2 from well 

 before the angle, 3 from before the angle, 4 from the angle, discocellulars very weak 

 in male, less so in female ; 5 from above the middle of the discocellulars, 6 stalked 

 at a third from the angle with 7 and 8, which are stalked close to the apex, 9 absent, 

 10 from the cell close to the angle, 11 from the cell just beyond the middle. 

 Secondaries with two internal veins, 2 from well before the angle, 3 and 4 from the 

 lower angle or stalked on a short stalk, 5 from above the middle of the discocellulars, 

 7 from the cell, 8 curved highly and sharply to the costa at the base, then in an 

 even curve, shortish. Genitalia : Clasps, almost spherical, tapered off from the 

 sphere slightly for the outer half, and truncate shortly at the apex. Girdle short, 

 stoutish, curved forward, rapidly fused into the extremely ample tegumen, which is 

 of unusual size, lobed at the back (i.e., towards the abdomen), but of an evenly 

 curved hood-shape in front, with strong deeply-curved falces, shortly serrated on 

 the outer curve. Penis-sheath short, fairly stout, gradually tapering down in a 

 waved outline to the extremity. 



The species belonging to this group are almost purely eastern, R. 

 betulae, in fact, being the only European species, as B. quercus is the 

 only European Bithynid. Superficially, on the upperside, the Buralid 

 species are not particularly like R. betulae as we know it, having the 

 whole of the upperside of the wings, except the costal tip and outer 

 margin of forewing, or the costal tip only, orange, the apex and 

 margin, or apex alone, being of the fuscous colour that is familiar 

 to us in the males of R. betulae. The mode of development of this 

 particular facies is, however, well seen in what is probably an 

 eastern form of 2?. betulae known as elwesi, Leech, and dealt with 

 later, in which the female has the arrangement of colour character- 

 istic of the allied eastern species. But, whilst the uppersides of the 

 other species show such considerable resemblance to ? elwesi, the 

 undersides are somewhat modified, and, in some instances differ very 

 considerably from the betulae type ; this difference extends in two 

 directions, one in the development of an antemarginal, and not 

 marginal, orange band with silvery edges (see group A, infra), the 

 other in the development of numerous transverse black lines, which 

 gives it an appearance quite sui yeneris, and at the same time does 

 away with all the markings more or less characteristic of the under- 

 sides of the other species of the group (see group C, infra). The 

 following summary of the Buralid species in the British Museum 

 collection may prove interesting : — 



A. With antemarginal band of oi'ange spots crossing underside of all wings, and 



edged with silvery lines. 



a. The first nervule of hindwing not developed into caudal appendage— 



Corkana — rapkaelis, Obth. (type), tinmen, Leech. 



b. The first nervule of hindwing developed into caudal appendage — 



QssURlANA michaelis, Obth. (type), gabrielis, Leech. 



B. With marginal band of orange spots bordering all wings on underside ; hind- 



winars tailed — 



