38 BULLETIN 31, UNITED STATES NATIONAL MUSEUM. 



CHILOSIA. 



Cheilosia Meigen, System. Beschr., iii, 296, 1822. 

 Cartosyrphua Bigot, Aunal. Soc. Eut. de France, 1883, 230. 



Moderately large to rather small species, metallic black, or black- 

 green, rather thickly pilose, sometimes almost quite bare. Head hemis- 

 pherical, scarcely broader than the thorax. Anteimai short, small, third 

 joint rounded or a little oval, never elongate, with a basal, bare, pubes- 

 cent, or i)lumose arista. Face black or metallic green, rarely some- 

 what reddish below, thinly pilose or pollinose, or quite bare; a little 

 below the middle with a tubercle, usually thence more sharply concave 

 to the slightly projecting oral margin; near the eye, with a more or less 

 distinct, parallel, slender groove ; in ]»rofile the lower part sometimes 

 produced downwards and forwards, at other times nearly perpendicular. 

 Eyes pilose or bare, contiguous in the male. Front in female never 

 wrinkled, usually with one or more linear depressions ; in the male the 

 frontal triangle more or less swollen, with an impressed longitudinal 

 line or pit. Scutellum rarely reddish on the border, sometimes along 

 its margin with a row of bristly hairs. Abdomen longer than the 

 thorax, elongate oval, never slender ; of five or six segments. Legs 

 simple, rather weak. Marginal cell of wing open, third vein gently 

 convex anteriorly, anterior cross vein towards the base of discal cell ; 

 outer anterior angle of first posterior cell always acute. 



In Europe this genus comprises nearly a hundred species, and it is 

 not probable that more than one-third of our species are known. The 

 flies are inconspicuous and not very active. The sexes differ much, in 

 not a few cases, in the color and length of the pile, in the color and 

 size of the third antennal joint, and in the markings of the abdomen, 

 which in the male is sometimes velvety opaque on the disk ; moreover, 

 in the female the face below, the humeri, and border of the scutellum, 

 are sometimes reddish or yellowish. 



TABLE OF SPECIES. 



1. — Eyes pilose 2 



Eyes bare g 



2. — Wiugs yellowish at base ; pile on dorsum of thoi-ax light colored .... 4 



Wings not lighter at the base ; the veins blackish ; pile of dorsum black . 3 



3.— Antennie black ; eyes densely pilose; face but slightly concave in profile below 



the antennae (^) occidentalis 



AntenuaB yellow; eyes ihiuly pilosis; face considerably concave below the iiii- 



tennseC?) (See Appendix.) hoodiensis 



4.~The face extends considerably below the eyes; the distance from anteuua^ to tip 

 of tuliercle ranch greater than thence to lowest part; above the tubercle 



in profile gently concave lasiophthalma 



Face not much produced downward; in profile considerably concave below the 

 anteuna3 5 



