130 DIPTERA OF NORTH AMERICA. [PART IV. 



nifying power shows it distinctly. The stigma is short and 

 rounded. The tip of the auxiliary vein is about the middle of 

 the length of the wing ; the subcostal cross-vein at a moderate 

 distance before this tip ; the tip of the first longitudinal vein is 

 at a comparatively short distance beyond the tip of the auxiliary 

 vein, almost opposite the tip of the sixth longitudinal vein, and 

 but little beyond the inner end of the submarginal cell. The 

 second longitudinal vein originates before the middle of the 

 length of the wing; the prsefurca is gently arcuated, and (in 

 both species which I have before me) of nearly the same length 

 with the remaining portion of the second vein, or a little shorter. 

 The marginal cross-vein, placed very near the end of the first 

 longitudinal vein, divides the marginal cell in two nearly equal 

 halves ; this cross-vein is almost in a line with the inner end of 

 the submarginal cell and with the small cross- vein; the third 

 longitudinal vein is arcuated ; the discal cell somewhat elongated, 

 its inner end narrowed ; the great cross-vein is nearly opposite 

 the small one ; the fifth longitudinal vein is straight ; the sixth 

 nearly so ; the seventh gently arcuated. 



The two species which I have before me (a North American 

 and a Mexican one) have nearly the same venation ; only in the 

 North American species the discal cell projects on the inside 

 of the cross-veins, whereas in the Mexican one the marginal 

 cross-vein and the inner ends of the submarginal, first posterior, 

 discal, and fourth posterior cells are all in one line. The venation 

 of T. simplex Wied., as figured by that author (Auss. Ziv. I, Tab. 

 VI,. b, fig. 8) is nearly the same, only the marginal cross-vein is 

 a little beyond the inner end of the submarginal cell, and not in 

 a line with it. The wing of Rhamphidia scapularis Macq. 

 (Dipt. Exot. I, 1, Tab. X, fig. 1), which is undoubtedly a Teacho- 

 labis, has the same venation ; even the peculiar curve or ear, 

 formed by the first longitudinal vein before joining the costa, and 

 which is likewise perceptible in the two species before me, is 

 correctly represented by Macquart. 



The peculiarity of the venation of Teucholabis consists in the 

 shortness of the auxiliary and the first longitudinal veins; the tip 

 of the latter, for instance, is not much beyond the inner end of 

 the submarginal cell ; whereas, in the other Tipulidse, it is usually 

 more or less far beyond this end. The marginal cross-vein, being 

 near the tip of the first vein, is thus naturally brought in one line 



