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Transactions. 



diameter, 0-38 mm. Sculpture : Nil. Micropyle : Not observed. Shell : 

 Shiny, smooth, transparent, strong ; is firmly cemented to the leaf, and 

 persists at the commencement of the mine for many weeks filled with frass. 

 Colour : The empty shell appears white and shiny, and is easily found. 



Egg-laying. 



The ova are laid singly, and there are rarely more than one or two to 

 a single leaf. In all the cases I have come across the egg is attached to the 

 upper surface of the leaf, and with a marked preference for a situation in 

 the vicinity of the midrib or one of the coarser veins. I have noticed that 

 in the great majority of the species of leaf-miners which construct fairly 

 long galleries there is a preference for this site near the midrib or one of 

 the coarser veins, and the larva almost invariably commences to mine along 

 this boundary towards the outer margin of the leaf, in the region of which 

 the greater part of the mine will be constructed. In cases where the egg 

 is laid in more open spaces on the leaf there is no such immediate choice 

 of direction towards the outer margin, but once the larva reaches either 

 the midrib or one of the coarser side veins it will mine along it until it 

 reaches the outer portions of the leaf. The advantages of mining in the outer 

 parts are obvious ; but if the eggs are deposited with a definite idea it is 

 puzzling to account for their not being laid near the outer margin of the 

 leaf in the first place. It appears that it is really immaterial where the 

 egg is laid, as the larvae do not seem to suffer any inconvenience through 

 the egg not being attached to one or other of the ribs ; one is therefore 

 led to believe that the choice of any particular part of the leaf is not made 

 out of consideration for the future larva. 



The Mine. (Plate XLI, figs. 1, 2.) 



The mine is a long narrow gallery terminating in an expanded blotch, 

 and is constructed immediately beneath the upper cuticle of the leaf. Its 

 general direction is, as a rule, from within towards the margin of the leaf. 

 The gallery portion in its earlier part has a beaded appearance when viewed 

 under a low power, owing to the actual width of the mine being somewhat 



Fig. 7. — Mine of A 7 , iwissopa in rangiora-leaf. Natural size. 



smaller than the diameter of the cells through which it passes ; all the 

 leaf-substance within the cell is eaten, and so the margin of the mine is 

 slightly scalloped in appearance. This early part of the mine is, as a rule, 

 far less tortuous than the later portions. The latter two-thirds of the 

 gallery is frequently very tortuous, and it may at times even cross the 



