HYDROPHORUS. 2 1 5 



the fore femora as usual, thickened towards the basis, on their 

 under side with two rows of thorn-like bristles, the inner row of 

 which reaches as far as their tip, while the exterior one stops 



already on the middle of the femora. Tibiae dark-green, the fore- 

 most uniformly fringed, upon their under side, with very short 

 thorn-like bristles. Tarsi black. Cilia of the tegulae fallowish- 

 yellow. llalteres with a dusky-yellowish peduncle, and with 

 blackened knob. Wings very long, tinged with gray, not darker 

 towards the anterior margin, with black veins up to the extreme 

 root; the end of the third longitudinal vein somewhat approaches 

 the fourth, so that these veins converge distinctly towards their 

 ends ; upon the posterior transverse vein and upon the convexity, 

 which the last segment of the fourth longitudinal veins crosses, 

 there is a somewhat more gray spot, winch is almost invisible to 

 the naked eye. 



Hab. Pennsylvania, District of Columbia. (Osten-Saeken.) 

 Observation. — It is difficult to determine, whether H. pincUa is 

 not one of those four species of Hydrophorus which Mr. Walker 

 has described as species of Medeterus. They agree in a good many 

 respects not only among themselves, but also with //. pirata, 

 while each of them exhibits also some distinguishing feature. 11. 

 viridiflos must be much more green, according to Mr. Walker's 

 statements, than //. pirata; besides, the cilia of the inferior orbit 

 of the former one are white, while those of the latter arc yellow; 

 moreover, its abdomen is conical and longer than the thorax, an 

 entirely uncommon character for a female of Hydrophorus, and 

 making it almost doubtful whether it really belongs to this genus ; 

 finally the veins of the wings are said to be brownish-yellow near 

 the root of the wing; these discrepancies are altogether too great 

 to justify the supposition that //. pirata can be identical with 

 viridiflos Walker. The face of Walker's female of //. glaber is 

 said to be covered with golden-yellow dust, the abdomen on the 

 upper side clothed with brownish-yellow hairs, the femora rather 

 stout and the halteres brownish -yellow. These differences are 

 likewise too important to admit the identity of //. j>ira/ti with //. 

 glaber. The face of Walker's female of //. chrysologus is said to 

 be also covered with golden-yellow dust ; the wings are said to be 

 brown along the anterior margin, ami to measure only three lines 

 in expanse, whereas they measure six lines in //. pirata Under 

 such circumstances the identity of these species is out of question. 



