Vol. VIII] ALDRICH— KELP-FLIES OF NORTH AMERICA 161 



3. Front with three pairs, the lower farther apart ; ant acr with 



scattered minute hairs between them (Bering Straits) 



bicruciata Stein. 



Front with two pairs, the lower farther apart, ant acr without 

 scattered minute hairs (California) evermanni, new species 



4. Tibiae mostly or wholly reddish-yellow 5 



Tibiae black, or paler only at the extreme base 6 



5. Middle femur below with two or three scattered bristles below 



from base to middle ; middle tibia with two small setae on front 



inner side (California ; Washington) rufitibia Stein. 



Middle femur without bristles below, middle tibia without setae 

 on front inner side (Atlantic Coast; Europe) ... .maritima Hal. 



6. Wings distinctly infuscated on apical half (Greenland) 



pictipennis Beck. 



Wings not infuscated apically 7 



7. Third antennal joint elongated, almost twice the second. (Alaska) 



antennata Stein. 



Third antennal joint but little longer than second 8 



8. Bucca (below the eye) as high as the eye (California) 



separata Stein. 



Bucca hardly over half the eye-height 9 



9. Numerous small hairs between the two rows of the ant acr .... 



costalis Stein. 



Ant acr in two rows without small hairs between 10 



10. Head nearly square in profile, prominent at antennae; sterno- 



pleural hairs long and abundant (Greenland; Arctic North 



America) ariciiformis Holmg. 



Head not so square ; hairs of sternopleura small, sparse 11 



11. Palpi wholly black (Arctic; Pacific, etc.) fucorum Fall. 



Palpi with basal half red (British Columbia) 



cestuum, new species 



Note. — The male is unknown in rejccta and bicruciata, and the female 

 in cestuum. I have placed these in the tables by analogy with the known 

 sex, but there is a chance of error. The unknown female of hinei I have 

 not ventured to place. 



