THE CANADIAN ENTOMOLOGIST. 385 



spur and segment. Head broadly rounded, wing venation regular. 

 Nectaries short and cylindrical, flanged at the end. Cauda broad and 

 very short ; antennte, body and legs with many small tubercles, each one 

 bearing a fine short hair. 



Chaitophorini. 

 Antennse except in (Sip/ia) always six-segmented; in Sif/ia there are 

 but five. Length variable, antennal tubercles wanting; antennje,- legs and 

 body covered with hair-like bristles. Fore wings with two oblique veins 

 and cubitus always twice forked ; hind pair with two cross-veins. 

 Nectaries variable in length and size, but never longer than one-tenth the 

 length of the body. The genera in this tribe are somewhat similar to 

 those in the tribe Callipterini, but are easily distinguished by the shorter 

 and heavier antennae and legs, as well as by the finer and more hair-like 

 bristles. 



Key to Genera. 



1. Antennae six segmented 2. 



Antennae five-segmented 5. 



2. Spur of sixth segment at least three times as long as the segment, and 



Cauda knobbed at the tip 3. 



Spur of sixth segment not three times as long as the segment, and cauda 

 broadly rounded and without a knobbed tip 4. 



3. Spur of sixth segment not more than five times as long as the segment, 



nectaries not longer than the sixth segment, and cauda 



constricted Ardaphis. 



Spur of sixth segment more than five times as long as the segment, 

 nectaries longer than the sixth segment, and cauda not constricted 

 at base of knob Chaitophorus. 



4. Antennae nearly as long as the body, and spur of sixth segment shorter 



than sixth segment Symdobius. 



Antennae about one-half the length of the body, and spur of sixth seg- 

 longer than the segment Thomasia. 



5. Antennae with but five segments and shorter than the body, nectaries 



very short and tapering, with a flanged mouth Sipha. 



Arctaphis Walker.^ 

 type A. populi Linn. 

 Antennae six-segmented, shorter than the body, and without antennal 

 tubercles ; spur of sixth segment as long or longer than the third and 



3. The Zoologist, 1870, p. 2000. 



