4 [June, 



to one-half of their length, which flap of membrane is turned back 

 over the wing exactly in the same manner as the brea?t flap of the 

 collar of a coat. It is usually covered with scales of a rather coarser 

 texture than those of the remainder of the wing, and placed, more or 

 less, in a different direction, so that, though they closely assimilate in 

 colour to the upper-side of the wing, the edge of the fold can generally 

 be seen, by the aid of a lens of slight power, from the different direction 

 of the scales, even though the fold may be pressed very closely down 

 to the surface. When, by any accident, this fold is raised, the space 

 beneath is seen to be thinly clothed with shining white scales, some of 

 which take the form of long hairs, and lie longitudinally under it, but 

 if the fold is turned forward, these hairs rise up and even form a most 

 delicate fan-like tuft, similar to that on the fore-legs of male Hypenidce. 

 I have a FenMerimia showing this very beautifully. 



In examining the Peroneae, none of which are furnished with the 

 fold, it will at once be noticed that, in many species, such as Teras 

 effractana, the Leptogrammce, Peronea hastiana, abietana, umhrana, 

 Logiana, and others, the shoulder of the strongly arched costal margin 

 is rough from projecting scales. It is exactly this portion with its pro- 

 jecting scales which in so many species is doubled back and forms the 

 *'fold." 



In what may be regarded as its typical state, the fold is, as I have 

 already said, a narrow slip of doubled-down margin, extending from 

 the base one-third or one-half the length of the anterior margin ; 

 Spilonota, Lithographia, Phloeodes, Poedisca, Catoptria, and Halonota, 

 of Wilkinson, for examples ; but in Ptycholoma Leclieana and Capua 

 ochraceana it occupies more than one-half the costal margin, and in 

 Ditula angustiorana and Pardia tripurictana fully two-thirds, and in 

 these four species it is very neatly folded down throughout its length. 

 Perhaps Ditula angustiorana may be regarded as an exponent of the 

 highest exaggeration of this structure, for its fold is also so hroad as 

 to occupy one-third of the width of the wing near the base. 



Lozotcenia Podana {pyrastrana) and costana have the short, nar- 

 row, typical fold, but L. rohorana, xylosteana, and rosana have, in 

 addition, the middle portion of the costal margin rolled back very dis- 

 tinctly to the same extent as it infolded down in D. angustiorana. 



In L. unifasciana the fold does not commence at the base, but, at 

 a short distance, begins gradually a long fold, which occupies — folded 

 or rolled — a large portion of the costal margin. In L. sorhiana and 

 Lafauryana it is placed still further from the base, and is quite desti- 



