1893,] 269 



at others short and twisting, and hidden away in a corner of the 

 blotch, as happens in woolhopiella. Hence it would appear that the 

 gallery was the primitive form, and that the blotch came as an after- 

 development, a view that is strengthened by other considerations as 

 well. The so-called vermiform mines, which form blotch-like patches 

 on the leaves, are galleries, folded back upon themselves over and over 

 again in a series of coils. They owe their form to the circumstance 

 that the larva confines its operation to the narrow space bounded by 

 two parallel ribs, for as soon as it is brought up by the rib on one 

 side, it turns sharp round until brought up again by the rib on the 

 other side, and so on backwards and forwards in this zigzag fashion. 

 Usually strips of tissue are left between the coils, but occasionally 

 the latter intercommunicate freely, and the mine might very well pass 

 for a blotch, were it not that the broad and winding frass-track still 

 remained to indicate its true nature. That some blotches may have 

 originated from these vermiform mines seems likely enough, though 

 probably most of them are merely the natural development of that 

 tendency which some galleries have to widen rapidly and out of all 

 proportion to the growth of the larva, so that it is sometimes hard to 

 decide whether they shall be called galleries or blotches. I alluded 

 just now to one blotch, in which no sign of a gallery can be detected. 

 This is the mine of argentipedella. It is more or less circular in shape, 

 with a central black spot, under which the larva lies curled up a large 

 part of its time, only coming out to eat at intervals, and is in con- 

 sequence a long time feeding up ; in all which particulars the habits 

 are rather those of a Tischeria than of a Nepticula. 



Now for a word about the galleries. They may be subdivided 

 into wide and narrow galleries, of which the latter is by far the more 

 numerous class. Then the kind of course they pursue is of import- 

 ance ; whether fairly straight, in which case the mine commonly ruiis 

 alongside a rib ; or curving and twisting, of which the vermiform mine 

 already described is the most striking form. Neither must the manner 

 of their commencement be neglected, for even here useful distinctions 

 are to be found. In some species it is long and hair-like, in others 

 again short and coarse ; and whilst in some the mine will strike out 

 at once boldly from the site of the egg, in others it curls and twists 

 about in its vicinity, and often forms little bunches of convolutions, 

 in the coils of which islets of leafy tissue are caught, and being cut 

 off from the general circulation, quickly die, so that the mine seems 

 to start from a brown dead patch in the leaf ; of which continuella 

 offers a good example. But of all the characters of the gallery none 



