ANNETTE F. BRAUN. 321 



flatteued head, the hirva being able to coii:«iiiiie but a few layers of 

 parenchyma cells directly in fi-ont of it. 



The mine retains its flat blotch-like character until after the sev- 

 enth moult. The larva then lines the loosened epidermis with silk 

 and by contraction produces from one to three narrow folds or 

 ridges. Beneath this folded portion the floor of the mine is thinly 

 covered with silk. Then the larva, lying on its back, spins a flat 

 semi-transparent sheet of silk, oval or nearly circular in shape, 

 attached around its edges to the floor of the mine (Plate XX, 

 Fig. 12 j. Beneath this, along its long axis, the pupa is formed. 

 The pupa, which is protruded from the mine in emergence, is thrust 

 through a transverse slit near one end of the flat cocoon. Such a 

 cocoon is formed in all but a few of the species of which the life 

 history is known. 



In almost all of the species, however, this cocoon is only made in 

 the brood of which the imagoes are to appear in the same summer. 

 In a later brood, the hibernating period, with one or two exceptions, 

 is passed in the larval state. In a number of species, hibernation 

 takes place beneath the folded epidermis. In most cases, however, 

 an especially prepared silken lined chamber is formed. After the 

 floor of the mine is loosely covered with silk, the upper epidermis is 

 fastened down in a circular or oval outline, and the whole cavity is 

 then lined with silk. Ample space is provided by a characteristic 

 oval or hemispherical projection upon the underside of the leaf. 

 The change to pupa occurs in the spring. 



The moths of this group may easily be recognized by the fact that 

 the white markings of the forewings are always externally dark 

 margined, often densely dusted with black scales behind. In some 

 cases there is, in addition, a slight internal nuirgin consisting of a 

 few dark scales near the costa. The markings consist of white cos- 

 tal and dorsal streaks, usually ol)lique. Opposite streaks may unite 

 to form a fascia, either outwardly angulated or straight. Vriiere 

 the fascia? are straight, they are nearer the base on the dorsal mar- 

 gin. The apex of the wing is often densely dusted with black 

 atoms, this efl'ect being produced by the black tips to whitish scales. 

 Sometimes these black tips form a distinct marginal line, which 

 passes around the apex and usually extends to the tornus. This 

 line is always present, but where the apex is not dusted, is not 



TRANS. AM. ENT. SOC. XXXIV. (41) OCTOHEK. 190b 



