NOVEMBER, 1859. 63 



from the apex of the discoidal cell a single vein to the tip. 

 The median nervure sends two veins to the inner margin 

 near the tip. In Desmodiella there is but one subcosto- 

 marginal vein. In the posterior wings both the subcostal 

 and median nervures are simple. 



There are two larval forms in this genus. In the first, the 

 head is much longer than broad, acutely ellipsoidal, with the 

 sides rather thick and rounded ; the body is cylindrical, sub- 

 moniliform, and the thoracic rings somewhat swollen. In 

 the second, the head is thin and flattened, with the mandibles 

 forming an appendage in front ; the body flattened, deeply 

 incised and mammillated on the sides. In both groups 

 there are three pairs of thoracic feet, three of abdominal, and 

 a terminal pair, but shorter in the second than the first. 



The larva? mine the upper and under side of leaves, the 

 larva? of the first group usually throAving the leaf into a fold, 

 and feeding from the margins of the mine to the centre ; 

 those of the second* forming a flat mine, sometimes a rather 

 broad linear tract, and sometimes an irregular blotch, their 

 mandibles being capable of working only in a horizontal 

 direction. They change into pupa Avithin the mine, some 

 weaving a firm cocoon, some suspended in a web, and some 

 forming a cocoon of grains of excrement and silk, or con- 

 structing the outline of a cocoon with them. The cocoons 

 of the second group are shown on the separated epidermis as 

 a circle, and an almost hemispherical protuberancef on the 

 under surface. 



The perfect insects rest with the antennae thrown backward 

 beneath the wings; some with the head slightly elevated, 

 others with the head applied to the surface and the body 

 behind elevated. I think the majority of the species here 

 described assume the latter position, with variations in the 

 angle formed with the surface on which they rest. 



* I doubt much whether we have in Europe anything resembling this second 

 group among the larvae of the American species of Lithocolletis. II. T. S. 

 t This seems to be a very striking peculiarity. H. T. S. 



