18 ARKIV FÖR ZOOLOGI. BAND 8. NIO 9. 



on the 2nd joint, we may, in my opinion, safely conclude 

 that the cushion at least partly represents that joint. Whether 

 the two sensillas are those usually to be found at the distal 

 end of the 2nd joint; or whether one of them represents the 

 3rd joint is difficult to tell. 



Finally, in the last instar of Phyllocnistis (fig. 65), the 

 antennas are even more reduced than in Nepticula, being 

 represented by a pair of small, subventral oval areas, with 

 two small papillas and a hair. 



Summa ry. 



The antennas of most of the leaf-miners are no more 

 reduced than that they still preserve three joints with the 

 usual number of papillas and hairs on the 2nd and 3rd joint. 



The review of their structure made above has revealed 

 several important facts. 



Thus, the reduction of the number may begin either at 

 the top or at the base of the antennas. 



In Tischeria (fig. 20) we see the beginning of the reduc- 

 tion of the basal joint, it being witbdrawn into a fold of the 

 cuticle; in Cemiostoma (fig. 27), and the young Gracilaria 

 (fig. 24), we notice how the basal joint has completely dis- 

 appeared; and in Nepticula (fig. 25) we find that to all ap- 

 pearance also the 3rd joint is either atrophied or only re- 

 presented by one of the papillas. 



Further, we notice that in the sap-feeders the antennas 

 are less reduced than in most of the tissue-feeders; and an 

 examination of the position of the antennas and the shape of 

 the head-capsule in the resp. genera throws light on this feature. 

 In Phyllocnistis, Lithocolletis (fig. 62) and Ornix (fig. 60) the 

 mouthparts form a distinct lobe at the anterior margin of 

 the capsule which is set off from the rest by a neck-shaped 

 constriction. 



It is in these lateral incurvations that the antennas are 

 placed, and consequently they are only slightly exposed to 

 pressure against the walls of the mines. 



In Cemiostoma and Nepticula (fig. 14), on the other 

 hand, the mouthparts do not form any such anterior lobe, and, 

 moreover, in the latter genus the antennas are placed fur- 



