( xxxiii ) 



among the wliite butterflies that have long been familiar to 

 all entomologists. 



The first of these four is the fine butterfly which Leech con- 

 sidered to be a form of Pieris extensa, Poujade, and to which 

 he gave the varietal name eurydice. Its aspect at once suggests 

 that it belongs to the group to which it is convenient to apply 

 the generic name Ganoris ; the group, that is, which includes 

 our common whites, brassicae, rapae and napi. This genus 

 or section is characterised by a very peculiar form of plume- 

 scale, and an inspection of this structure in P. extensa eurydice 

 at once shows that it is a true Ganoris. As will be seen from 

 the drawings, the scale is very much like that of G. napi, 

 though curiously enough it is on the average considerably 

 smaller. 



The next species, P. davidis, Oberth., has been accounted 

 an Aporia, i. e. a member of the group to which our Black- 

 veined White belongs. But here again the plume-scale solves 

 the question of affinity, for it has the unmistakable character of 

 a genuine Ganoris, and bears no resemblance to that of Aporia. 

 The third species, P. delavayi, Oberth., is far away from the 

 former two. It is closely allied to the well-known form 

 agathon, Gray, for which, with its nearest relatives, Mr. Butler 

 established the generic name Metaporia. No Metaporia 

 known to me has any scent-scales at all, though the ordinary 

 scales of the wing have a distinctive character of their own, 

 and are distinguishable without difficulty from those of 

 Ganoris. 



The last species on the list, P. goutellei, Oberth., has been 

 placed, like G. davidis, in the genus Aporia. But its affinities 

 are clearly with agathon rather than with crataegi, as it has 

 no plume-scales, and its ordinary scales have the Metaporia 

 character. Aporia and Metaporia are no doubt closely related, 

 and without further examination I am doubtful as to how far 

 the distinction between them will hold. 



The Pierine group to which daplidice, Linn., cJiloridice, Hiibn., 

 glauconome, Klug, and some other forms belong, is conveniently 

 known as Synchloe. I have here added drawings of the plume- 

 scales of the two first-named species, in order to show how very 

 distinct they are from the rapae and napi group. As I have 



PROC. ENT. SOC. LOND., II. 1914. C 



