178 Proceedings of the Biological Society of Washington. 



Paragus Latreille. 



P ANGUSTiFRONS Loew. — Falls Church, Va. , July 24, 1913, Greene; 

 April 26, June 11, 16, 22, and July 6; Glencarlyn, Va., June 23, Banks; 

 Virginia near Plummers Id., Md., June 18, 1916, H. L. Viereck; Rock 

 Creek, Md., June 15, 1913, Shannon; Maryland near Plummers Id., 

 June 2, 1916, McAtee; Beltsville, Md., July 4 and 9, 1916, McAtee. 



P. BicoLOR Fabricius. — Maryland near Plummers Id., April 23, 1914, 

 Cabin John, Md. , August 18, 1914. Linnieville, Md. , July 4, 1913, Rosslyn, 

 Va. , May 18, 1913, Shannon; Falls Church, Va., July 21 to August 1, 

 1913, Greene; June 16, July 6, August 9 and September 7; Chain Bridge, 

 Va. , June 14, Banks; Vietch, Va. , July 18, 1915; Four-mile Run Valley, 

 Va., June 11, 1916, McAtee. 



P. DIMIDIAT0S Loew. — Originally described from the District of Columbia 

 (Centuria quarta, p. 63). Knowledge of this form seems not to have 

 advanced since Williston published his Synopsis. He then said: "The 

 structural differences given for this species may justify its separation from 

 P. tibialis, but in the examination of a considerable material which I 

 have compared with specimens of the latter from Europe I have not been 

 able to satisfy myself of differences sufficient to justify specific separa- 

 tion" (p. 20). 



P. TiBiAMS Fallen. — More common than the other species of the genus; 

 April 18 to October 30. The species of Paragus fly close to ground in 

 slightly moist places near or in partial shade, but occur also on flowers. 



Pipiza Fallen. 



P. ALBipiLOSA Williston. — Plummers Id., Md., April 23, 1914, Mary- 

 land near Plummers Id., May 8, 1914, Cabin John, Md., April 18 and 

 29, 1916, Shannon; April 30, 1915, A. H. Pottinger; C. & O. Canal, 

 Seven-Locks, Md., April 27, 1915, April .30, 1916, L. 0. Jackson; Great 

 Falls, Va., April 28, 1915, Shannon; May 12, 1911, S. A. Rohwer; April 

 30 (one specimen, doubtfully belonging here; I do not think this can be 

 the P. femoralis, Banks). 



P. CALCARATA Loew. — Washington, D. C, June 13, 1916; Maryland 

 near Plummers Id., April 28, 1914, Shannon; Great Falls, Va., April 20, 

 1913, F. Knab. Loew's description of this species mentions the occur- 

 rence of processes only on the hind coxae. There are processes on the 

 middle coxae also of the two specimens from this region and of another 

 in the National Collection from New Hampshire. The type may have 

 these structures obscured. European dipterists assign species with 

 similar structures and with the hypopygium conspicuously set ofi" from 

 the remainder of abdomen to the genus Cnemodon. All the characters 

 used, however, are secondary sexual ones, hardly suitable for the sepa- 

 ration of genera. The females are in no way peculiar. 



P. FEMORALIS Loew.— Dead Run, Va., May 9 and 19, 1916, May 23, 

 1915, Shannon; Great Falls, Va., May 2, 1916; Plummers Id., Md., May 

 10, 1916, McAtee. 



