( xlix ) 



somewhat variable, is easily distinguished from that of other 

 members of the genus, e. g. rapae and canidia. It is roughly 

 cordate, broad at the base, and narrowing more or less abruptly 

 into a distal portion, the sides of which are usually parallel. 

 The base is furnished with well-marked cornua, which are 

 generally inclined to one another, and frequently cross behind 

 the stem which unites the lamina with the accessory disc. 

 The latter structure is moderate in size and somewhat chestnut- 

 shaped in outline. 



" On examining Mr. Williams' specimens of bryoniae, I found 

 that in one of them the scent-scales could not be distinguished 

 from those of an ordinary English napi. In another, however, 

 the proportion between the proximal and distal portions of 

 the lamina was very different, the latter being much broader 

 than in the usual form. The third specimen was intermediate 

 in character, but on the whole tended towards the normal. 

 The only conclusion that could be come to was that there was 

 no specially distinctive character attached to the scales of the 

 form bryoniae. 



" It occurred to me, however, that it might be interesting to 

 widen the outlook by examining scales from specimens of 

 P. napi from various localities, in order to gain some idea of 

 the limits of individual variation in these structures, and also 

 to ascertain, if possible, whether such variations as exist could 

 be correlated with others, e. g. in the genitalia, or with con- 

 ditions of topography. 



" I soon found that the great comparative breadth of the 

 distal part of the lamina, which was apparent in one of the 

 specimens of bryoniae, was carried to an even greater extent in 

 a specimen from Algeria, and perhaps more strikingly still 

 in one from Cannes. The Algerian specimen is also remarkable 

 for the great development on many of the cornua of a curved 

 spiny process, an indication of which is visible in a few of the 

 bryoniae. This last feature may also be seen in the scales of 

 a specimen from Crieff, in Scotland; here also a broadening 

 of the distal part of the lamina is evident ; while in a second 

 specimen from the same locality, the relative proportions are 

 very nearly the same as in the second bryoniae. 



" Other continental specimens do not differ from the English 



PROC. ENT. SOC. LOND., II. 1916 D 



