4 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 64 



chromatic plate the customary yellows, browns, and black are not 

 well differentiated and due allowance for color values must be made 

 in interpreting the figures. 



This paper is a contribution from the Zoological Laboratory of the 

 State College of Washington in Pullman. 



KEY TO THE GENERA OF CLUSUDAE. 



1. CoBta broken beyond humeral crossvein, auxiliary vein curving forward to end 



considerably before termination of first vein; postverticals strong and distant; 

 arista but little longer than antenna; eyes microscopically pubescent; cross - 

 veins widely distant; no cruciate bristles or preapicals . Acartophthalmus Czerny . 

 Costa not broken near humeral crossvein, but weakened or broken near end of 

 auxiliary vein which extends parallel with first vein even at tip; postverticals 

 approximate, sometimes absent; arista two or more times the length of the 

 antenna, short only in Hendelia; eyes bare 2 



2. All fronto-orbitals reclinate; prothoracic bristle vestigial or absent; cruciate 



bristles present on middle of front 3 



Foremost pair of fron to-orbital bristles convergent or proclinate 6 



3. Cruciate bristles arising from the orbits; three or four fronto-orbitals of equal 



length; preapicals present Czernyola Bezzi. 



Cruciate bristles arising from middle frontal stripe 4 



4. Crossveins approximate, sections of fourth vein 1:4; preapicals present; presutural 



dorsocentrals present or absent 5 



Crossveins distant, sections of fourth vein 1:3; no preapicals, postverticals, or pre- 

 sutural dorsocentrals AUometopon Kertesz . 



5. Antennae distant, arista thick; postverticals absent; lunule covered; two fronto- 



orbitals Hendelia Czerny . 



Antennae close together, arista thin; postverticals usually present; lunule exposed; 

 two or three fronto-orbitals Clusiodes Coquillett. 



6. Cruciate bristles present on middle frontal stripe; crossveins distant, the sections 



of fourth vein 1:3; ocellars long 7 



Cruciate bristles absent 8 



7. Postverticals absent; no prescutellar setae; prothoracic bristle strong. 



Clusia Haliday. 

 Postverticals small; prescutellars present; prothoracic bristle short. 



Paraclusia Czerny. 



8. Postverticals absent; first vein bristly; ocellars small; crossveins approximate. 



Chaetoclusia Coquillett. 

 Postverticals present; first vein not bristly 9 



9. Preapical bristles present on middle tibiae; crossveins usually distant, the anterior 



crossvein nearer middle of discal cell, the last two sections of foiu-th vein usually 



about 1:3 10 



Preapical and prescutellar bristles absent; crossveins approximate, the sections of 

 the fourth vein about 2:1:4; ocellars small Heteromeringla Czerny. 



10. Ocellar bristles long; presutural dorsocentrals present 11 



Ocellars short; no presutural dorsocentrals Sobarocephala Czerny. 



11. Prothoracic bristle strong 12 



Prothoracic bristle short; three fronto-orbitals Apiochaeta Czerny. 



12. Arista lanceolate, densely pubescent; three fronto-orbitals; four scutellar bristles. 



Phylloclusia Hendel. 

 Arista slender; four fronto-orbitals; six scutellars Alloclusia Hendel. 



