NEPTICULA ARCUATELLA. 807 



tinctly angulated). The imago of N. arcuatella is very difficult to 

 distinguish from that of N. atricollis. They are of about the same 

 size, but the latter is blacker, and the fascia is broader and more 

 brilliant. N. arcuatella, too, has the anterior wings a little broader, 

 and the curve in the fascia which, in this species, takes place on the 

 fold, seems in N. atricollis to occur at about the middle of the wing, 

 i.e., nearer the costa (Stainton). N. arcuatella may be recognised by 

 the tips of the cilia of the anterior wings being greyer, not so white, 

 and by the paler legs. The fascia has the same direction as in N. 

 antjuUfasciella ; but is very narrow and less conspicuous (Heinemann). 



SEXUAL DIMORPHISM. The frontal tuft of the male is generally pale 

 luteous or ochreous, in the female more or less of a brownish-fuscous, 

 especially at the hinder part, yet some males occur with brownish and 

 females with yellowish frontal tuft (Heinemann). 



EGG-LAYING. The egg is laid on the upper surface of a leaf of 

 Potentilla fraf/ariastrum or Frayaria vesca (Stainton). Nolcken calls 

 attention to this record, and states that he examined 4 mines, in all of 

 which the egg was laid on the underside of the leaf. 



MINE. The first part of the mine consists of a much contorted 

 gallery, in which the dark brown excrement is conspicuous ; the gallery 

 then becomes wider and less contorted, and at last widens out into a 

 small blotch, in which there is very little excrement. The blotch is 

 not formed until quite the end of the larval period. Heinemann 

 describes the mine as " long, tortuous, with a slender frass-line." 

 Frey notes the mine, in strawberry, as " long irregular, very much 

 twisted, commencing as a very narrow gallery, running in and out 

 along the margin of a leaf, with a very fine dark brown frass- 

 line ; later the mine widens gradually, and the frass becomes blackish, 

 but still forms a very fine stripe with distinct margins." This descrip- 

 tion reminds one of that of N. frayariella. Nolcken calls attention to 

 the discrepancies between various authors, in their descriptions of the 

 mine, mode of egg-laying, etc. He describes the mine in Tormentilla 

 (? crecta) as being without the pale margins, and the closely twisted 

 spot (as described by Stainton). It begins moderately twisted, with 

 perceptible width,, which increases very gradually. After some time 

 it expands into an irregular spot, which, owing to the small size of 

 the leaf, often includes the earlier part of the mine. The frass, which 

 completely fills the mine from its commencement to the blotch, 

 shows three different forms of arrangement that may appear in either 

 stage of the mine, e.g., the frass may be granular and united into little 

 heaps of varying size, or the granular pellets may be placed close 

 together and form a regular row, or the pellets may be irregularly 

 scattered, whilst, sometimes, band-like tracts of excrement are formed 

 as if the deposit had been liquid. In the latter part of the mine the 

 frass sometimes marks the path of the larva, at other times it is scat- 

 tered irregularly. Seen from above, the frass appears black, held against 

 the light it is somewhat transparent and greenish, composed of patches 

 of unequal density, the darker patches leading insensibly into the form in 

 which the excrement forms an opaque black band, often irregular, but 

 conspicuous. Nolcken compared his with mines received from Heine- 

 mann, and found them very similar, although the latter had not 

 always the tortuous beginning, were without light margins as far as 

 the blotch, and had the excrement more granular and not deposited in 



