I. TRÄGÅRDH, LEPIDOPTEROUS LEAF-MINERS. 33 



Its mouth-parts are of a type entirely different from 

 those hitherto met with, but are nevertheless highly instruc- 

 tive, and show how, even amongst the leaf-miners, similar 

 results may be achieved in different ways. 



The first thing we notice, on examining the mouth-parts 

 of the larva of Tischeria (fig.36) is,that the floor of the mouth- 

 opening projects considerably beyond the roof, the top of the 

 hypopharynx, the maxillary palpi and the palpiger being 

 visible from above in front of the labrum. The latter has a 

 very complicated structure (figs. 35, 36), being deeply con- 

 cave in the middle, with large tufts of hairs at the latera] 

 angles and on the ventral side, where the sides are thickened; 

 on the median side of these are 3 pairs of large unciform ap- 

 pendages. The mandibles are in the basal half of the inner 

 edge provided with fine fringes (fig. 39). The maxillse (figs. 

 51 & 52) are of a very peculiar shape in so far that the 

 palpiger has the shape of a large, ovoid, flattened disc, 

 densely clothed with minute hairs; on the upper side of it 

 there is an oblique ridge, on the inner side of which there 

 are 3 pairs of hooks, of the same shape as those at the 

 ventral side of the labrum. The maxillary palpi are small 

 and on a level with the palpiger. Lobus externus and lobus 

 internus are small, 2-jointed, and placed in the middle of the 

 palpiger, on its upper side. 



This remarkable development of the palpiger in forming 

 a pair of large lamina which meet one another, and form 

 the floor of the mouth-opening, is probably connected with 

 the moving backwards of the spinneret, the first beginning 

 of which modification we traced in Eriocrania. In Tischeiia 

 (fig. 50) the spinneret has moved still further backwards, and 

 does not participate in the formation of the floor of the 

 mouth, but is replaced by the hypopharynx which has in- 

 creased in size, so as to form the middle of the floor, the 

 rest being the palpiger. 



The labium is very peculiar in one respect, viz. almost 

 the whole spinneret and the palpi are concealed underneath 

 a thin, horizontal fold of the mentum. The palpi are 2-jointed, 

 the basal joint being almost coalesced with the men tum. 

 The hypopharynx is densely clothed with narrow, pointed 

 appendages, and conical in outline. 



Arkiv för zoologi. Band 8. N:o 9. 3 



