xxxiii, '221 ENTOMOLOGICAL NEWS 267 



less complete impressed curved line extending- from humerus 

 on each side to the transverse median impression. 



The species vary much in color but in structure they are 

 quite constant. No use has previously been made of the 

 armature of the fifth sternite of the males in systematic papers 

 though its shape has been mentioned, and previous authors 

 have omitted any mention of the curved thoracic depression. 



Nothing is known of the larval habits of the genus ; the 

 adults occur on various flowers. 



Key to Males. 



1. Hind tibia with a distinct elevated chitinized beaklike projection at 

 apex on ventral surface which is either acutely pointed or com- 

 pressed from each side ; apical abdominal sternite without minute 

 spinules, only fine hairs present 



Hind tibia either transverse at apex on ventral side or with a short 

 apically rounded scooplike production 



2. Small species, about 5 mm. in length ; black and yellow in color, the 

 apical process on hind tibia beaklike and slightly curved ; hind tro- 

 chanters without minute black setulae.. . . flavomaculata Malloch. 



Large species, 8-9 mm. in length 



3. Reddish species ; hind femora unicolorous rufous ; hind tibia with 

 the apical process rounded at tip and compressed from each side ; 

 hind trochanters without black setulae, 



armatipes Malloch var. rufa Malloch. 



Black species with yellow markings ; hind femora largely black ; 

 hind tibia with the apical process beaklike, slightly curved, not com- 

 pressed from both sides ; hind trochanters with some black 

 setulae armatipes Malloch. 



4. Scutellum transverse at apex, the two long setulose hairs separated 

 by ftiore than half the basal width of scutellum ; hairs at apices oi 

 fourth and fifth abdominal sternites strong, but no short stout 

 spinules present, fifth produced lobuliform at posterior angle on left 

 side occidentalis Malloch. 



Scutellum regularly rounded posteriorly, the setulose marginal hairs 

 if only two in number separated by much less than half the basal 

 width of scutellum 



5. At least the fifth sternite with some short setulae or spinules 

 apically '' 



No short spinules on fifth sternite. only fine hairs present 11 



6. Both fourth and fifth sternites with some short spinules apically..? 

 Only the fifth sternite with short spinules apically 9 



7. Fifth abdominal sternite almost transverse at :ipt \, not noticeably 

 produced in the form of a rounded lobe at left posterior anle ; the 



