6 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



Great numbers of this species were collected in the 

 vicinity of Monterey, Calif., during the entire month of 

 July, 1896. It was particularly abundant in company with 

 H. afflictus, in a salt-marsh between Monterey and Del 

 Monte. 



At first sight H. cotisaiigumeus appears to be identical 

 with H. crenatus. The more important points of difference 

 are the following: H. consanguineus is larger, has stouter 

 infra-ocular cilia, and many of these are deep black, 

 whereas they are all pale in H. crenatus. The tegular cilia 

 of the male consanguineus are stout and black, those of 

 H. crenatus v^Q-dk. and yellow; the anterior surface of the 

 fore coxae of the former is covered throughout with black 

 hairs, in the latter only a portion of the surface thus is cov- 

 ered. The hypopygium of the male crenatus has white 

 lamellse with a narrow, sharply defined black border, where- 

 as the pale portions of the lamellae of consanguineus are 

 suffused with the black of their borders. The wings have 

 the same neuration in both species, but the short stump on 

 the distal segment of the fourth vein is often lacking in 

 crenatus. There are also differences in the antenna: in 

 consanguineus the second joint is proportionally longer than 

 it is in crenatus, and the yellow on its mesial surface is 

 more restricted. 



Polymedon Osten Sacken. 



This remarkable genus, first described by Osten Sacken 

 in his "Western Diptera " and based on a single species, 

 P . jlabellifer O. S., from California, has been extended by 

 Aldrich to include a second species from the West Indies 

 (P. su-perbus Ald.^. Among my material I find a single 

 female specimen from Arizona and evidently distinct from 

 the two known forms. 



7. Polymedon castus, sp. nov. 

 Plate I, Fig. 8. 



Female. Length 5 mm. ; length of wing 7 mm. Proboscis fuscous, fringed 

 with small white hairs and dusted with white along its edge. Palpi and 

 face covered with silvery white dust; the latter, which is convex below and 



