THE CANADIAN ENTOMOLOGIST 377 



by the presence of peculiar, colourless, thread-like, homogeneous, 

 chitinous structures which we have named circumfili because they 

 invariably run around the segment. They originate or arise from 

 the interior of the segments, are presumably auditory in nature 

 and are discussed by Europeans under the names of arched fila- 

 ments (verticili arcuata and filets arques) and bow whorls (Bogen- 

 wirtel), since these common names aptly describe the structures as 

 seen in the males. These organs in the females generally form a 

 slender girdle near the base and distal portion of the enlargement 

 on the flagellate antennal segments, the two being connected by one 

 or two longitudinal threads. In the males the development may 

 be very diverse. In the case of the male Asphondylia the circumfili 

 consist of a more or less variable series of extremely tortuous, 

 slightly elevated threads reaching from the base to the apex of the 

 segment. In the Itonididinariae the circumfili of the male are 

 frequently prolonged into a series of bow-like loops girdling the 

 basal and apical enlargements of the antennae; one on each in the 

 bifili and in the trifili with two on the distal enlargement. The 

 loops of the circumfili or bow whorls may be simply conspicuous 

 sinuosities as in Caryomyia or greatly prolonged on one side and 

 having a length equal that of the entire segment as obtains in 

 Aphidoletes and Bremia. A unique form of circumfili occurs in 

 the genus Winnertzia. Here these structures greatly resemble 

 minute, horseshoe-like appendages, one on each face of the segment, 

 the produced free ends extending beyond the apex of the enlarge- 

 ment, while the supporting vertical threads give the appearance of 

 a series of nails. 



The peculiar circumfili, quite distinct in structure from audi- 

 tory setae, suggest our latest means of communication, the much 

 vaunted "wireless," and present distinct analogies thereto. Both 

 respond to impulses conveyed through air. It is possible the 

 circumfili are "tuned" to vibrations unrecognizable with our finest 

 instruments, and while the devices of men may convey signals 

 several thousand miles, there is no reason for thinking that these 

 unique antennal structures are relatively less efficient. 



Palpi: — -The normal number of palpal segments appears to be 

 four, though these organs may become greatly reduced in any one 

 of the tribes and in one genus, Oligarces, appear to be wanting. 



