DIPTERA OF BAJA CALIFORNIA. 617 



45. Eristalis LATiFRONS Lw. San Francisco county, 

 Cal. One male in bad condition is doubtfully referred 

 to this species. 



46. Eristalis obsoletus Wied. El Taste, Baja 

 California (Eisen). September. Thirty- one females. 

 Length, 9 to 12 mm. The scutellum is quite yellow, 

 with only a tinge of ferruginous. The spots of second 

 abdominal segment are obscure reddish, rarely with a 

 yellowish tinge. 



47. Eristalis tenax L. California. Two males, 

 two females, and the puparium from which one of the 

 males emerged. 



48. Eristalis tricolor Jaenn. El Taste, Baja 

 California (Eisen). September. Two males and two 

 females. Hind tibice narrowly yellow at base, front tibi£e 

 yellow on nearly basal half, middle tibia; and metatarsi 

 almost wholly yellowish. They have the abdomen more 

 extensively clear yellow than a specimen from Guan- 

 ajuato. 



49. Xylota sp. aff. obscura Lw. California. A 

 single male specimen in bad preservation seems to come 

 nearest to this species. It differs from description as 

 follows : 



Length, 11 mm. Antennae brown, arista yellowish. 

 Scutellum purplish, same color as greater part of abdo- 

 men. Abdomen blackish; second segment on each side 

 anteriorly, third more broadly on each side and on hind 

 border, and fourth almost entirely shining purplish. Base 

 of tibice brown like rest of legs. Abdomen rather whitish 

 pilose. 



50. Syritta pipiens L. California. One female. 



