266 LITHOCOLLETID.®. 
upper cuticle, some beneath the under cuticle, but the larva of 
no species is known to mine indifferently the upper or under side 
of a leaf. ‘The larva, in the process of its mine, contorts the leaf 
more or less, the leaf curving towards the side on which the larva 
is at work; the larva carpets the loosened skin with silk, and 
purposely pulls it so tight as to cause the loosened skin to pucker, 
whereby the opposite side of the leaf naturally curves. Mr. Boyd 
has suggested that the natural shrinkage of the silk may, without 
any extraneous assistance from the larva, cause the puckering of 
the loosened skin. Many of the larve have the third and fourth 
segments considerably enlarged. The larvae of some species form 
cocoons of silk, sometimes of very fine texture ; others interweave 
the grains of excrement into the cocoon; a few do not construct 
any cocoon. Most of the species are double-brooded, appearing 
in the perfect state in May and August, and the larvee feeding in 
July and October ; a few of the latter brood remain in the larva 
state throughout the winter, but in most of the species the pupa 
state is assumed before the commencement of winter, and many a 
withered brown leaf blown hither and thither, at the mercy of 
every gust, contains throughout the winter a living pupa, to ap- 
pear in the following spring as one of these splendid insects. 
The genus may be tabulated as follows :— 
a. Anterior wings with a hook in the cilia. Species 1-3. 
a a. Anterior wings with no hook in the cilia. 
6, Anterior wings dark, with a white, whitish, or silvery basal streak. 
ec. The basal streak dark-margined on both sides. Species 4-9, 
19, 20. 
ec. The basal streak dark-margined only towards the costa, Spe- 
cies 10, 12, 17, 26. 
ccc. The basal streak with no dark margin. Species 11, 13, 
14-16, 18, 21-25. 
6b. Anterior wings white, with dark streaks or fasciee. Species 27- 
30, 41. 
666. Anterior wings dark, with no defined basal streak, but with 
two or more pale fascia. Species 31-40. 
1. Roboris, Zell. Isis, 1839, p. 217; Id. L. B. i. 174. pl. 1. f. 4. 
—foborella, Sta.—Roborifoliella, Dup, lis anticis niveis, macula 
parva dorsali aureo-brunnea basim versus, fascia lata obliqua a basi 
costa fere ad medium dorsi, aweo-brunnea, pone medium lineis quatuor 
costee, una dorsi nigris introrsum fuscescente-marginatis, puncto rotundo 
apice atro, caudulam ciliarum emittente. Wxp. al. 4 lin, 
Head white, with a few fuscous hairs. Face and palpi white. An- 
tennee whitish, with fuscous annulations. Anterior wings white, with 
a small golden-brown blotch on the inner margin near the base; az 
