40 



ARKIV FÖR ZOOLOGI. BAND 8. N:0 9. 



on the leaves for the larva to walk upon, is not a thread 

 but a very thin ribbon.» 



Chapman places Limacodes near Eriocephala, and con- 

 siders both as primitive forms. 



c) Sap-feeders. 



Our investigation into the structure of the labium and 

 maxillse of the tissue-feeders revealed some facts which enable 

 us to understand the extraordinary adaptations displayed by 

 the sap-feeders. 



U 



59, 



Gracilaria syringella, 1st instar. 

 Fig. 58. Head capsule, ventral aspect. X 155. 

 Fig. 59. Top of labium and palpi, ventral aspect. X 363. 



These were: 1) the reduction or modification of the 

 spinneret and labial palpi, 2) the increase of the hypopharynx 

 so as to form a thin lamina, constituting the »lower lip» of 

 the mouth-opening, 3) the great increase in size of the stipes 

 of the maxiUae. 



In the sap-feeders we find all these features; but the 

 speeialisation is carried to the extreme, so that several organs 

 are almost atrophied, whereas others have attained a very 

 remarkable size. 



It is not possible to place the genera examined in one 

 series, since in one of them, for instance, the shape of the 

 maxillse may be more primitive than in the others, whereas 

 at the same time the labium is more reduced. 



