26 



ARKIV FÖR ZOOLOGI. BAND 8. N:0 9. 



into the incisions of tbe other. The axes of rotation of the 

 mandibles are not parallell, but converge slightly dorsally, 

 this being, however, compensated by their edge not being 

 parallell to the axis. 



In fig. 37 the mandibles of a fullgrown larva of Gracilaria 

 syringella are delineated. 



39. 



Fig. 37. Fullgrown larva of Gracilaria syringella. Mandible, V 2 ven trål 



aspect. X 413. 

 Fig. 38. Eriocrania sp. Mandible, ventral aspect. X 413. 

 Fig. 39. Tischeria ekebladhella. Mandible, ventral aspect. X 386. 

 Fig. 40. Nepticula sp. Mandible, ventral aspect. X 386. 



On external view, only 4 teeth are discernible, the two 

 median ones being the largest, with serrated dorsal edge ; the 

 dorsal edge is a thin blade set off from the upper tooth by 

 a small incision. 



On inner view we notice, however, another smaller, ventral 

 tooth, thus in all 5 teeth. 



It is obvious that the flattening of the head pointed out 

 in a preceding chapter, which characterizes the head of the 

 miners has also influenced the shape of the mandibles and 



