GIReUMEDE; OF With CE CHDOMY PDA! 
These peculiar antennal structures are what have been more 
generally known as arched filaments. They were first discov- 
ered by Targioni-Tozetti in 1888 and independently observed 
by Kieffer in 1895. They are most highly developed in the male 
Diplosids | fig. 43], consisting in these forms of neatly homogeneous 
whorls of long, looped filaments extending around the en- 
largements of the segments. Each loop is closely fused to the 
base of its fellow, and the entire whorl presents every appear- 
ance of being one structure. This peculiar development also 
occurs in female Diplosids, being represented in this sex by 
slightly elevated, nearly colorless threads supported by minute 
stalks. There is usually, in this sex, a circumfilum near the 
base and one near the apex of the enlargement of each segment, 
the two being connected by one or more longitudinal fili. There 
is very rarely a connection between the two or three citcumfili 
on a segment in the male Diplosid, though an evidently abnor- 
mal connection of this character has been observed in the case 
Oimcicmmale Om moO tiay tae a ime mica na Heltaiie. 72], Mle 
homologous character of these apparently different structures in 
the two sexes is confirmed by the fact that in the male Bremia 
[fig. 44] the basal circumfilum of the distal enlargement is low 
and exactly like that of the female. These structures occur not 
only in the Diplosids but also in practically all other Ceci- 
domylinae, not being present, so far as known to us, in the 
Lestreminae. The genus Lasioptera has these structures in a 
very simple form, they being in both sexes merely slightly ele- 
vated threads supported by slender stalks and joined on at 
_ least one face of the segment. Rhabdophaga and its allies have 
a similar arrangement, except that in the male there is a slight 
indication of greater specialization, and the same is practically 
true of Rhopalomyia. Vhe most striking variations on some 
accounts are those found in the Asphondyliariae. The circum- 
fili in the male Asphondylia [fig.. 38] consists of a more or less 
variable series of extremely tortuous, slightly elevated threads 
= 
* Read at the third meeting of the Entomological Society of America held 
at Chicago, Il, December 30, 31, 1907. 
395 
