I. TRÄGARDH, LEPIDOPTEROUS LEAF-MINERS. 37 



is reduced, contrary to most other larvae, where the basal 

 joint has more or less coalesced with the men tum (comp. p. 31). 

 On the dorsal side of the spinneret we notice a very remark- 

 able feature, a pair of narrovv, pointed appendages, situated 

 at the anterior margin of the labial complex. These seem 

 to be of great interest from a phylogenetical point of view. 

 As is well known, the spinneret is generally interpreted as 

 being constituted by the fusion of lobi interni and externi of 

 the labium; as far as I know, it has, however, not been pos- 

 sible to trace by degrees this procedure in different larvae. 

 It is thus of interest to find these two appendages in a 

 genus which, for other reasons, is considered a primitive 

 one; and one is led to presume that the appendages are 

 remnants of the lobi interni or externi. 



57. 



Fig. 57. Thread of silk spun for walking purpose on a glass-slide by 

 larva of Coleophora laricella, X 15. 



In Elachista (fig. 56) both the spinneret and the palpi are 

 essentially of the same type as in Nepticula, but both are more 

 reduced than in that genus. Thus the palpi are single-jointed 

 (or 2-jointed if the terminal appendage is reckoned as a joint), 

 and the spinneret is very short but comparatively very broad, 

 its width at the base equalling its length. Also in Elachista, 

 there appear to be some indications of the spinneret being 

 composed of the fusion of lobi externi and interni, its top 

 being divided into 4 small lobi. 



b) Review of the principal features exhibited by the 

 labium and maxillse of the tissue-feeders. 



One of the most characteristic features of the lepido- 

 pterous larvae is their spinneret and their silk-glands. 



It is not necessary here to dwell at length on all the 

 different ways in which the larva? make use of this organ. 



