144 NORTH AMERICAN DIPTERA. 



14. Antennae at base slightly separated l:)y a carina (body grey or partly 



rufous, with a well-defined black pattern). Gk.\phomyia Desvoid}'. 

 Antennae not separated by a carina. . . . . . .15 



15. Middle tibia; with a bristle on inner side; apical cell widely opened. 



Mesembrina Macquart. 

 Mesembrinella Giglio-Tos. 

 Middle tibia; without bristles on inner-side; apical cell somewhat nar- 

 rowly opened (C/jrtoneimi pt. preoc.) Morellia Desvoidy. 



16. Eyes pilose. . . . . . . . Myiospila Desvoidy. 



Eyes bare. ........... 17 



17. The first vein terminates at tip of costa; fourth vein with a distinct 



curvature near tip of wing (Ci/rtoiiriini pt. preoc.) 



MusciNA Desvoidy. 



The first vein terminates before the middle of the costa; fourth vein 



scarcely curved forward at its distal end. Clinopera v. d. Wulp 



5G. TACHINIDJ5. 57. DEXj/dM. 



Rather small to rather large, bristly flies, thinly or not at all 

 pilose, usually thick-set. Eyes of the male contiguous or more 

 approximated than in the female, pubescent or bare. Front 

 with a row of bristles on each side, descending to the antennae, 

 with or without orbital bristles. First joint of antennae 

 short; second joint usiuilly shorter than the third; third joint 

 usually more or less elongate, sometimes dilated or fissured; 

 decumbent; arista bare (Tachinidee), pubescent or ])lumose 

 (Dexijfdae), sometimes conspicuously jointed. Face always 

 with a well-marked median depression, which sometimes has 

 a carina in its middle. Proboscis sometimes elongate, but 

 usually short and with broad labella; palpi never with more 

 than one articulated joint, which is sometimes rudimentar}-. 

 Ocelli present. Abdomen composed of four or five visible seg- 

 ments ; with marginal and lateral and usually with dis- 

 cal bristles; sometimes nearly covered with strong, erect spines. 

 Legs usually ratlier stout; sometimes elongate and slender 

 (Dexifdvd); always bristly. All the veins of the wings simple; 

 basal cells large; three ])osteri(ir ('clls present, tlie first of which 



