I. TRÄGÅRDH, LEPIDOPTEROUS LEAF-MINERS. 



3. Shape of the head-capsule. 



a) Tissue-feeders. 



In the head capsule of any external feeder araongst the 

 lepidopterous larvse we notice that the dorsal side is longer 

 than the ventral one (fig. 8), but yet the hind margins are 

 nearly on the same leve], because the head is bent obliquely 



Fig. 1. 

 Fig. 2. 

 Fig. 3. 



Head-capsule of Cemiostoma labumella, dorsal aspect. X 300. 

 » » » Elachista sp., ventral aspect. X 206. 



» » » Nepticala sp., » » X 206. 



downvvards. In the leaf-miners, on the contrary, the head- 

 capsule is horizontal, and in many cases even flattened 

 dorsoventrally to an extreme degree (Tischeria, Nepticula). 

 This results, amongst other things, in the liind part of its 

 dorsal side being concealed in a fold of the prothorax; and this 

 has evidently proved a great advantage to the miners, since 

 this portion has not only increased considerably in length 

 (fig. 3), but its hind margin in many instances has also de- 

 veloped into thin blades (fig. 2). 



