112 DIPTERA OF NORTH AMERICA. 



the others. The ground color of the abdomen is more blackish 

 than that of the thorax, the posterior and the lateral borders of 

 the segments being usually more brown ; besides, the abdomen 

 is covered with a rather light dust and beset with small brown dots 

 coalescing near the lateral border into a row of obsolete spots, 

 and in the middle of each segment into a longitudinal spot, so that 

 a dark middle stripe, interrupted by the incisions, is formed. The 

 sixth segment, being clavate in the male, has a large blackish- 

 brown spot on each side, leaving in the middle a grayish or whitish 

 mark, resembling, as it were, a cup. The ground color of the 

 femora is little visible, being covered with light dust and speckled 

 with black dots ; immediately before the tip they are surrounded 

 with an almost black more or less visible ring, and an almost con- 

 colorous spot before this ring on the under side. The tibia? are 

 yellowish-brown, with the tips blackish ; the tarsi have the same 

 color as the tibire, but are generally a little paler; usually the ante- 

 rior ones have the three last joints, and sometimes a great part of 

 the first, blackened, whereas in the remaining tarsi only the two 

 last joints, or even the last alone, is blackish. The wings are more 

 guttated than reticulated ; the color of the posterior part is more 

 gray; immediately along the longitudinal veins, and in the neigh- 

 borhood of the costa, it is much darker and almost brown. The 

 largest drops, the color of which is almost white, are scattered 

 over the posterior part of the wing ; on the anterior part they are 

 placed near the longitudinal veins ; on the costa, between the tips 

 of the first and second longitudinal veins, there are only three 

 small clear quadrangular spots. 



Hob. Washington. (Osten-Sacken.) 



Observation. A series of specimens enables me to compare this 

 species with the closely allied European Tet. umbrarum Linn. The 

 resemblance of both is so great that I cannot but suspect that they 

 are identical. No difference of structure existing between them, 

 the larger size and browner color of Tet. pictipes alone afford a 

 constant distinguishing character. Future observations will per- 

 haps enable us to decide whether Tet. pictipes is merely a climatic 

 variety of Tet. umbrarum or a different species. 



Note. I possess a specimen from Great Slave Lake, H. B. T., and 

 have seen another from Maine, both perfectly agreeing in size and color 

 with the European specimens. Is this fact to be considered as a proof of 

 the identity or of the diversity of T. pictipes and T. umbrarum? The 

 answer to this question appears to me far from certain. 0. S. 



