126 DIPTERA OF NORTH AMERICA. [PART III. 



the greater or smaller extent of the spots on the wings, especially 

 by the relative position of the stigmatical spot to the one cover- 

 ing the small crossvein, and by the separation or coalescence of 

 both. 



1. C. obstiniconiis n. sp. % 9 .—(Tab. VIII, f. 20.) Polline ex 

 cinereo luteseente vestitus, tertio autennarura articulo fusco-nigro, 

 pedibus lnteis, alarum macula stigmaticali et limbo vense transversalis 

 mediae fasciolam arcuatam efficientibus. 



Covered with a grayish-clay-yellow pollen ; third antennal joint brownish- 

 black, feet clay-yellow ; the spot at the end of the stigmatical cell and 

 ' the one covering the small crossvein form a curved crossband. Long, 

 corp. % 0.21 ; 9 cum terebra 0.25 ; long. al. 0.2—0.21. 



The first two antennal joints brownish-ferruginous-yellow, or 

 brownish-yellow ; third joint brownish-black, of medium breadth ; 

 arista black. Scutellum upon its edge only indistinctly yellow- 

 ish-brown. Abdomen without any trace of dark crossbands, 

 except that the pollen, towards the posterior portion of the seg- 

 ments, becomes more brownish-gray in a hardly perceptible 

 degree. The first joint of the flattened ovipositor is only 

 moderately long, very broad; its truncature very broad also; the 

 coloring and the pollen are the same as those of the abdomen. 

 Feet clay-yellow ; tarsi, with the exception of the basis, more 

 or less strongly infuscated ; the only male in my possession has 

 the front femora very much infuscated upon the greater part of 

 the posterior side ; it is not probable, however, that this is a 

 constant sexual character. The first spot on the wings extends 

 from the first to a little beyond the fourth vein ; the spot lying 

 upon the end of the stigmatical cell is more or less completely 

 coalescent with the one covering the small crossvein, and forms 

 with it a rather oblique, distinctly arcuated crossband ; the other 

 spots have nothing peculiar about them. 



Hab. Nebraska (Dr. Hayden). 



2. C. ocliricorilis n. sp. 9« — (Tab. VIII, f. 21.) Polline ex cinereo 

 lutescente vestitus, segmentis abdominalibus postice anguste fusco- 

 limbatis, antennis ex-ferrugineo ochraceis, pedibus luteis, alarum macula 

 stigmaticali et limbo venae transversalis media? in fasciolam rectam 

 conjunctis. 



Covered with a grayish-clay-colored pollen; the segments of the abdomen 

 with narrow brown borders posteriorly ; antennae ocbre-brownish, the 



