144 NORTH AMERICAN DIPTERA. 



14. Antennae at base slightly separated by a carina (body grey or partly 



rufous, with a well-defined black pattern). GRAPHOMYIA Desvoidy. 

 Antennae not separated by a carina 15 



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



MESEMBRINA Macquart. 

 MESEMBRINELLA Giglio-Tos. 



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

 rowly opened (Ct/rtoneura 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 (Cyrtoneura 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 



56. TACHINIM;. 57. DEXIID^E. 



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 usually shorter than the third; third joint 

 usually more or less elongate, sometimes dilated or fissured; 

 decumbent; arista bare (Tachinidse), pubescent or plumose 

 (Dexiidae), 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 rudimentary. 

 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 rather stout; sometimes elongate and slender 

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

 basal cells large; three posterior cells present, tlie first of which 



