284 A. L. MELANDER. 



The species E. sociabilis Williston * (synonym Rhamphomyia 

 abdita Coquillett) is not included in the table as it is a true Rham- 

 phomyia, and was originally given as Empis only through a typo- 

 graphical error. 



Two of Walker's species, agasthusf and reciproeaX have been 

 dropped, and, likewise, Loew's poplitea has been omitted from the 

 table on accouut of insufficient characterization. 



In attempting to place species with the aid of the following table, 

 too much reliance must not be placed on the wording, as this genus, 

 and indeed the whole family as well, is in a state of extreme " mor- 

 phological restlessness." The instability of the species manifests 

 itself often in the coloration, often in the chsetotaxy. Stress is laid 

 in the key on the number of scutellar and metapleural bristles, but 

 this character is variable and often misleading, so that only within 

 certain limits can it be accepted. Moreover, greasy, immature, or 

 rubbed specimens may often lead one astray ; thus it is only after a 

 comparative knowledge of a number of forms that a determination 

 may be relied upon. 



More or less yellow species, i.e., pleurse largely yellow, thoracic dorsum at least 



partly yellow along the sides 2. 



Black, gray, or brown species ; pleurse never yellow 22. 



2. Occiput black, more or less cinereous dusted 3. 



Occiput yellow 17. 



3. Thorax and abdomen unicolorous, red • 4. 



Thorax and abdomen more or less vittate with blackish 5. 



4. Stigma distinct; anterior branch of the third vein perpendicular; body with 



no black bristles rubida Wheeler et Melander. 



Stigma wanting; second submarginal cell acute ; body with black bristles. 



rufescens Loew. 



5. Halteres blackish ; thorax with a longitudinal black stripe. 



leptogaslra Loew. 

 Halteres whitish or reddish 6. 



6. Dorsum of thorax evenly blackish ; autenuije black 7. 



Dorsum of the thorax with darker vittse 10. 



7. Sides of the thorax and venter with long yellow pile. 



laiiiveiitris Escholtz. 

 Not yellow pilose 8. 



8. Tibiffi apically blackish lori pedis Coquillett. 



Tibiae yellow 9. 



9. Abdomen opaque amy tis Walker. 



Abdomen shining gladiator sp. nov. 



* Kans. Univ. Quart., vol. ii, p. 76. 



I List of Dipt. Ins, iii, p. 496. 



X Trans. Ent. Soc. Lond., N. Ser., iv, p. 147. 



