North American Diptera. 26 



tlie fourth vein, the last section of fourtii vein oblique, sin- 

 uous, closing or much narrowin}>; the broad first posterior cell. 

 Large, or very largo species. Microstylcm 



Face pilose or hairy, more convex. .... 11 



11. Abdomen cylindrical, not narrow at the tip, elongate; near the 



base of second and third segments with white poUinose emar- 

 ginate cross-bands ; wings dark. Dizonias 

 Abdomen less elongate, with five or six white pollinose cross- 

 bands 12 



12. First posterior cell open, scarcely narrowed, face broad. 



Laphystia 

 First posterior cell mucij narrowed or closed. . . Triclis 



18. Antennse elongate, composed of five joints; nearly bare species. 14 



Antenna? less elongate or short, of three joints, with or without 



a short or slender style. .15 



14. First and second joints of antennae of nearly equal length, third 



elongate, fourth short, fifth elongate and densely pubescent ; 

 third and fourth not lobed at tip Ceraturgus 



First joint about three times as long as the second, third elon- 

 gate, fourth and fifth of nearly equal length , third and fourth 

 at the tip with two lobes or processes, reaching to about the 

 middle of the following joint. . . Myelaphus 



15. Style of antenna; short, thick, obtuse, not easily distinguishable 



from the third joint, or, if so, forming apparent joints ; anten- 

 niB more or less elongate. ...... 16 



Terminal style small, more slender than the joint, apparent; 

 antennae shorter 18 



16. Nearly bare species ; face flattened, bare except below. Small, 



or rather small, species, shining or metallic black, with nar- 

 row or cylindrical abdomen and large wings. . 17 

 Thickly pilose species, the bristles few and hair-like; antennae 

 situated upon a convexitj', thence receding to the facial tuber- 

 cle, which is situated upon the lower part of the face ; abdo- 

 men short; head narrow. ..... Dicolonus 



17. All the tibiae and the hind femora with short, strong setae. 



ECTHODOPA 



Hind femora without such seta-. .... Dioctria 



