THE CANADIAN ENTOMOLOGIST 379 



suited for the study of adaptation in numerous ways than the gall 

 midges, a large group which up to recent years has been almost 

 ignored by students. 



Explanation of Plates XII and XIII. 



1 . Antenna of Microcerata spinosa male, showing 9 short 

 segments. This organ is shorter in this species than the palp. 



2. Sixth antennal segment of Col podia diervillcs male. Note 

 the greatly produced distal stem. 



3. Fourth antennal segment of Prionelliis gramince male, 

 shoAving the conical shape and the peculiar whorls of long setae 

 arising from distinct crenulate chitinous ridges. 



4. Fifth antennal segment of Karschomyia viburni male, 

 showing a binodose, almost trinodose structure of the segment 

 and the peculiar circumfili or bow whorls. 



5. Seventh and eigth antennal segments of Monardia toxico- 

 dendri female, showing the general shape. of the segments and the 

 characteristic stemmed disks. 



6. Fifth antennal segment of a Rhopalomyia female, showing 

 the generalized type of segment and the low circumfili commonly 

 occuring in the female Itonididinarice. 



7. Sixth antennal segment of Asphondylia monacha male, 

 showing the low, very tortuous character of the circumfili. 



8. Fifth antennal segment of the pear midge, Contarinia 

 pyrivora male, showing the binodose character of the segment and 

 the two well-developed circumfili, the latter characteristic of the 

 bifili. 



9. Fifth antennal segment of Caryomyia caryce male, showing 

 the short though plainly sinuous circumfili, the three on a segment 

 being characteristic of the trifili. 



10. Fifth antennal segment of Aphidoletes hamamelidis male, 

 showing its binodose character, circumfili, and particularly the 

 greatly produced loops and seta? on the dorsal aspect. 



11. Sixth antennal segment of Winnertzia calciequina female, 

 showing the peculiar horseshoe-like circumfili attached to opposite 

 faces of the subcylindric segment. 



12. Extended ovipositor of the nun midge, Asphondylia 

 monacha female, showing the basal pouch, the thick eversible basal 

 portion of the ovipositor and the highly developed needle-like 

 terminal part. 



