3o6 NEW YORK STATE MUSEUM 



reaching from the apex of the segment to its base, usually in 

 the form of two more or less well defined loops. In the female, 

 the circumfili girdle the segment near its basal fourth and 

 apically and are united on one face by a longitudinal filum. 

 The genus Schizomyia [fig. 39] in the Asphondyliariae is nota- 

 ble because of its thicker, more elevated and more strongly 

 convolute circumfili, though the general plan is similar to what 

 obtains in Asphondylia. The genus Cincticornia [fig. 41], on 

 the contrary, presents remarkable modifications, in that the 

 male antennal segment may be girdled by 10 or more low 

 anastomosing circumfili, while the antennal segment of the 

 female is literally inclosed in a coarse reticulation of these 

 peculiar structures. Furthermore, it should be added that these 

 strikingly modified circumfili are accompanied by marked and 

 relatively constant variations in other organs. The male Dip- 

 losids, as noted above, present the maximum development in 

 these structures. The genus Contarinia [fig. 43], for example, 

 is more easily separated from other genera by the occurrence 

 of but two even circumfili in the male, than by the apparent 

 uniformity of the enlargements of the antennal segments. The 

 genera Bremia and Aphidoletes [fig. 44, 45] are remarkable in that 

 the slender circumfili are greatly produced on one side, even 

 to a length equal twice that of the entire segment. The Epi- 

 dosariae show considerable variation in these structures, there 

 being a marked tendency toward the production of long, slender 

 tips at the apex of the segment. The most unique type is found 

 in the genus Winnertzia [fig. 48] , in which the circumfili appear 

 to be modified to form horseshoelike appendages, one on each 

 face of the segment, the produced free ends extending beyond 

 the apex of the enlarged portion of the segment. 



These structures appear to have no homologies in related 

 groups, unless they are analogous to the peculiar, apparently 

 fleshy hypodermal structures protruding from relatively large, 

 symmetrically placed orifices on the antennal segments of the 

 Campylomyzariae [fig. 31] and of certain Chironomidae. 



The origin of these peculiar structures is not easy to deter- 

 mine. Kieflfer, several years ago, suggested that they might be 

 remnants of hypodermal lamellae, the margins of which had 

 become thickened and chitinized, while the membranous portion 

 disappeared. At that time we accepted his theory tentatively, 

 as we had nothing better to ofifer. It is now extremely difificult 



