LETTER OF DECEMBER 12TH, 1857. 9 



larvae. The enclosed sketches represent one of the larvae, 

 two views of the pupa, a mined leaf, and the neuration of 

 the wings of the perfect insect. I endeavoured several times 

 to make a creditable representation of the insect, but was 

 compelled unwillingly to give it up, being too much of a 

 novice in colouring. I send you the imago more for the 

 purpose of being assured I have classified it correctly, than 

 as an addition to your cabinet. I find with perhaps un- 

 necessary feelings of chagrin, that the pins sent me by 

 Messrs. Edleston and Williams, and marked No. 20, are too 

 large for its thorax, and consequently prevent the wings 

 being properly set. This may be owing, however, to want 

 of delicacy in manipulation on my part, but I can perceive 

 no difference between 19 and 20, except that the former is 

 slightly longer than the latter. Should there be no observable 

 difference between them in diameter ? 



When I first noticed the leaf mined by this larva, I sup- 

 posed it was tenanted by a leaf-spider, and examined it with 

 no expectation of finding a " Micro." The larva mines the 

 underside of the leaf, and it is situated always on one side of 

 the midrib, sometimes near the base of the leaf, sometimes 

 about the middle, but most frequently near the free extremity. 

 The epidermis of the inferior surface of the leaf covering the 

 mined portion is a pure white colour, and is stretched over 

 a fold made by the margin being drawn towards the midrib. 

 This fold is seen on the upper surface as a ridge in a brownish 

 patch of variable size and shape. The larva feeds on the 

 cellular substance found between the network of veins in the 

 leaf, leaving them untouched and perfectly cleaned. It is 

 doubtless owing to this circumstance that the fold in the leaf 

 is formed, and increases as the external membrane is denuded 

 of cellular matter, and its nutrition prevented by the opera- 

 tions of the little miner. I supposed, at first, that the 

 epidermis of the inferior surface must be lined with silk, but 

 find on examination that it is not, and therefore the fold 

 cannot be produced by any agency of the larva directed to 

 that end. I noticed, however, several instances in which 



