80 Cincinnati Society of Natural History. 



form of the head and trophi represented at figure 3 is assumed. The 

 form is now very different, but consists of the same organ, with the ad- 

 dition of the rudimentary labial palpi (r/). The antenna; are represented 

 in figs. 1 and 3 at [h). In the first stage, the ocellus or pigment spot is 

 single on each side of the head («), just behind the base of the antennae, 

 but after the first moult, two e3'e spots appear on each side (as in fig. 1), 

 and these continue to grow during the first five stages. In these five 

 stages, owing to the form of the larva, and of its trophi, it eats only a 

 few layers of cells of parenchyma next to the cuticle of the leaf, and 

 therefore the size of the mine being ascertained, it is easy to determine 

 not the weight but the comparative quantity of food taken in each 

 stage. For further information as to the genus, I must refer to the 

 various entomological publications of this country and Europe; and as 

 connected more especiall}^ with the subject of my present remarks, I 

 refer especially to some papers by me in the organ of the Cambridge 

 Entomological Club, Psyche, for November and December, 1877, and 

 May to August, 1878, and a note in a later number of the same volume. 

 In those papers I stated that owing to the difficulty of making 

 suitable observations on larvjfi concealed more or less in their mines, 

 and which invariably die on being removed from their mines, I had 

 not then been able to toUow any species through all of, its larval 

 changes so as to observe its different moults ; but that b}^ collecting 

 and observing large numbers of mines and larvfe, and examining and 

 counting the cast skins in the mines, I had arrived at the conclusion, 

 that the number of moults was eight, and could not be less than seven. 

 Since then I have been more successful, and have traced the entire 

 life histories of several species, and I find that the number of stages 

 of larval life is seven. I stated also in Psyche, Iog. cit., that at certain 

 moults, as I then believed at the 7th in the flat and ornatella groups, 

 and at the 5th in the cylindrical group, a change in the form of the 

 trophi from thai given at fig. 1 to that of fig. 3 took place. This 

 change does take place; but it occurs at the 5th moult in the first two 

 groups, and at the 3d in the cylindrical group. I also stated that it 

 was at this change that the spinneret is first developed. This is in- 

 correct. It then first becomes perfect, and previously is of no 

 functional importance; but it may be discovered in a rudimentary con- 

 dition in the first stage of larval life. I also then stated that at each 

 moult the larva adds to its length, the length of the larva at the end of 

 its first stage, and this is true of the first five stages, not of the remain- 

 ing two. As stated, loc. cit., this rate of growth ceases at the moult at 

 which the change takes place in the form of trophi, but as above just 



