306 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. Kieffer, 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 offer. It is now extremely difficult 
