Nineteenth annual Meeting. 127 



42. Between the third and fourth longitudinal veins, and sub-parallel with them, 



crossing the anterior cross-vein, a spurious longitudinal vein, or, when rarely 

 not present, the first posterior cell closed a considerable distance from the 

 border; eyes never extraordinarily large; abdomen never with bristle. 



SYBPHIDa; 



Spurious vein never present; first posterior cell never closed before the margin; 

 eyes very large, including the largest part of the head; small species. 



PiPDNCDLIDa; 



43. Proboscis horny, elongate, often folding back near the middle; abdomen never 



with bristles; tibiae without terminal spurs (or, if with them, the face with a 

 median ridge, and the proboscis folding); first posterior cell closed or nar- 

 rowed CoNOPiDa: 



Proboscis fleshy and not elongate, (or if elongate and slender, with or without a 

 median hinge, the abdomen with distinct bristles, or the antennae plumose) . .44 



44. Tegulas large; face with sub-antennal vertical grooves or depression. {Muscidce 



calyptratce) 45 



Tegulae small MusciD^ aoalyptbat^ 



45. First posterior cell widely open, not narrowed in the margin Anthyomyid^ 



First posterior cell closed, or more or less narrowed 46 



46. Antennal arista wholly bare Taohinid^ 



Antennal arista distinctly pubescent or plumose 47 



47. Arista bare on the distal part; dorsum of abdomen rarely bristly before the distal 



part SAEOOPHAGIDiE. 



Arista plumose or pubescent to the tip 48 



48. Dorsum of abdomen bristly; legs usually elongate Dexid^: 



Abdominal segments without bristles, except sometimes somewhat near the tip. 



MusciD^ 



49. Wingless flies, parasitic upon bats; head not flattened, folding back upon the 



dorsum of the thorax; first joint of tarsi not abbreviated NxoTEEiBiDa; 



Winged or wingless flies, parasitic upon birds, quadrupeds, or bees; head flat- 

 tened, sunk into a shallow emargination of the thorax; first joint of the four 

 anterior, or all, tarsi abbreviated Hippoboscid^ 



For the determination of the genera and species, a large number of papers must 

 be consulted, a list of which would be out of place here, and which, up to 1878, will 

 be found in Osten Sacken's Catalogue (Smithsonian, 1878), a work whose necessity 

 will be first to the student. Papers published since that time on North American 

 Diptera have been by the following authors: C. R. v. Osten Sacken, F. M. v. d. Wulp, F. 

 Brauer, V. v. Boeder, J. Mik, J. F. M. Bigot, F. A. F. Karsch, E. Burgess, D. W. Coquil- 

 lett, and the writer. The following list only, containing such papers as present tables 

 or descriptions of the North America genera, in the families named, may be given: 



Ceoidomyid^. Osten Sacken, Monographs of the Diptera of North America, i, 173, 

 Smithsonian Institution, 1862. 



BiiEPHABOCEBiD^. Locw, Rcvision der Blepharoceridae, Schles. Zeitschr. f. Entom. 

 (neue Folge), vi, 54, 1877. 



TiPULiDa:. Osten Sacken, Monographs N. A. Diptera, iv, Smithsonian Ins. 1869; Ber- 

 lin, Entom. Zeitschr. 1886, 153. 



