240 BRITISH LEPIDOPTERA. 



the egg, which is placed sometimes on the surface quite in the centre of 

 the leaf and away from any of the larger veins, at other times against 

 one, whilst on other occasions it is placed quite on the margin. 



Mine. — The mine, which looks like a fine, whitish, wavy, much 

 twisted line on the upper side of a leaf of Gewn urbanum, gradually 

 broadening as it advances, is quite invisible on the underside. It 

 measures probably, with the various convolutions, from 5 to 6 inches, 

 often doubles back on itself, and crosses and re-crosses the earlier part of 

 its path. It begins as a fine, slender, hair-like line, but at its termination 

 a good mine is 2 mm. wide. There are no sudden expansions of 

 the mine, at points corresponding with a larval moult, as one finds nor- 

 mally in certain species, and there is only one very distinct change 

 in the arrangement of the frass. The mine itself gradually and 

 regularly broadens with the growth of the larva, and the frass forms 

 a slender broken line, running through the centre of the gallery, with 

 a distinct margin on either side of the frass-line, the margin very 

 broad in comparison with the width of the frass-line, until almost 

 one-third of the gallery has been formed, when, although its regularity 

 is maintained, the frass resolves itself into distinct pellets, arranged 

 in a most orderly manner, and the distinct margin is maintained 

 until the termination of the mine. The quantity of frass is very 

 small, compared with that in the mines of some species, and 

 considering the size of the mine. Under a lens the upper epidermal 

 surface is seen to be raised or blistered, and the edge of the 

 mine tinged with reddish, the presence of the larva having evidently 

 discoloured the chlorophyll on the edge of the mine. Eppelsheim 

 notes that in some mines of X. gei, the frass is more densely grouped 

 and the margins more free in some than in others. Certain mines in 

 leaves of Patbufi corylifolius referred by Fletcher to this species, exhibit 

 considerable difference from the mines of N. <jei. They have a strong 

 tendency to run by the side of a rib as long as possible, and to go from 

 one rib to another ; they also are, as a rule, broader, and the frass in 

 the first part forms a continuous fine line, which alters, evidently 

 after a larval moult, into a much more diffuse arrangement of the 

 frass pellets, which are very regularly arranged individually, and form a 

 very broad band along the centre of the gallery ; in the last three 

 quarters of an inch of the mine the frass is scattered somewhat 

 irregularly. These differences may readily be seen with the naked 

 eye ; nor. is there in any degree so clear a margin on either side of the 

 frass-line in the mines in the leaves of Geum, as in the mines in the 

 leaves of IUibus. 



Length of larval life. — Eppelsheim notes that on Nov. 6th, 

 1888, he found a large radical leaf of Geum containing 14 mines, of 

 which 11 were still occupied by feeding larva? on the 21st, and the 

 last two did not leave their mines till the 29th, so that these occupied 

 at least 23 days in coming to maturity. On Dec. 1st, 1888, he 

 obtained 6 other mines containing feeding larva?, of which the latest 

 vacated its mine on the 15th. On Oct. 26th, 1889, a leaf containing 

 3 larva? was found ; one of these vacated its mine next day ; the 

 others were, however, very young. One of these remained motionless, 

 in its mine, and without feeding; until Nov. 3rd. It then fed until 

 Nov. 10th, when it stopped again until Nov. 19th, on which date it 

 commenced again to feed. Probably these cessation* marked the 



