Willistoi).] dl-j [May 19, 



phus.) Europe and "Western America. Very abundant in the Pacific re- 

 gions. 



PP. — Eyes of male without area of enlarged facets above ; front moder- 

 ately convex ; hypopygium not very small. 



Q. — Sixth abdominal segment of male as long as two preceding together, 

 but narrower, somewhat tubular, unsymmetrical ; on underside of 

 seventli segment two long linear sub-parallel appendages, arcuate, 

 bidenticulate at end, embedded in grooves when at rest. In the fe- 

 male fifth segment half as long as preceding. Scutellum much 

 raised, exposing metanotum Eupeodes. 



EuPEODES voLrcRis O. S., West Dipt., 329. Washington Territory, 

 Kern county, California. ! Nevada, Utah, Colorado, common. 



QQ. — Hypopygium without slender appendages, sixth segment of male 



not peculiar ; fifth segment of female one-third or one fourth as 



long as preceding. 



R. — Third longitudinal vein with a distinct sinuosity ; third joint of 



antenujfi elongate-oval ■ Didea. 



Table of Species : 

 a. — Third joint of antenn;e obtusely pointed; third longitudinal vein, 

 with a considerable sinuosity. Abdominal cross-band of second and 

 third abdominal segments broader towards, but not quite reaching, 



the lateral margin fitscipes. 



'HI. — Third joint of antennte more evenly oval; the third longitudinal 



vein less sinuous ; 

 /a— Abdominal cross-bands attenuated at outer ends, and usually quite 

 meeting the lateral margins : 

 Didea laxa O. S., Cat. Dipt. 245. While Mts.; Mt. Hood, Oregon ; 

 Washington Terr. ! 



bb. — Abdominal cross-bands nearly obsolete : 

 '1 Didea alcidice. 



St/rphus Alcidiee Walker, List, etc., iii p. 579. Hudson Bay Terr.; 

 Osten Sacken Cat. Dipt., 2d Ed., p. 244, note 205. 



A single specimen from Mt.' Hood, Oregon, resembles D. laxa very 

 much, but the two small oval yellow spots of the second segment, the re- 

 maining segments being dark metallic green with an opaque, black longi- 

 tudinal line, seem to indicate a distinct species, and apparently Walker's 

 Alcidiee. The generic differences of both these species, however, from 

 some species of ^yrphi {e.g., S. lapponicus), are feeble. 



RR. — Third longitudinal vein straight or gently curved ; third joint of 

 antennsB short oval , Syrphus. 



This genus appears to be a prominent one in the Western regions ; 

 many of the Eastern species appear, and others have strong resemblances. 

 Two si^ecies Avhich present well marked ciiaracters, I describe as new. 

 The following table contains, with the exception of dimidiatm. tai'satus, 

 and fumipennis, all of the known species north of Mexico. It is composed 



