186 DIPTERA OF NORTH AMERICA. [PART IV. 



triangle ; this is due to-the shortness and the obliqne course of the 

 prsofurca, the origin of which is a little beyond the middle of the 

 length of the wing; the tip of the pra^furca almost coincides with 

 the origin of the third longitudinal vein. The portion of the fifth 

 vein beyond the great cross-vein is at an obtuse angle with the 

 previous course of this vein ; the sixth longitudinal vein is gently 

 arcuated ; the seventh nearly straight. The forceps of the male 

 (Tab. Ill, fig. 13 from above, fig. 13 a from below) has two small 

 horny appendages which, in the state of repose, are closely 

 applied to the under side of the fleshy basal pieces ; hence, and 

 owing to their smallness, they are indistinct. The ovipositor of 

 the female is soft, obtuse, without any apparent horny lamels 

 (Tab. Ill, fig. 13^, side view; 13c, from abovie). This structure 

 of the ovipositor renders the recognition of the sexes very difficult 

 in dried specimens. 



The genus Cryptolabis (from xpurfroj, concealed, and xojSt;, 

 forceps) has been introduced by me in 1859 (Proc. Acad. Nat. 

 Set. Philad. p. 224), for a single species which I discovered in 

 Virginia. No other species has been added to it since. 



]. C. paradoxa 0. S. % and 9- — Thorace livido, nigro-vittato ; an- 

 tenuis nigris ; pedibus basi pallidis ; alis iinmaculatis. 



Thorax livid, with black stripes ; auteunse black ; feet pale at the basis ; 

 wings immaculate. Long. corp. 0.1 — 0.13. 



Syn. Crypiolahis paraduxa 0. Sacken, Proc. Ac. Nat. So. Phil. 1859, p. 225. 



Head blackish ; palpi and antennas black. The color of the 

 thorax is livid, but it is scarcely apparent between the black 

 stripes ; the intermediate stripe is double ; the lateral ones are 

 extended backwards beyond the suture ; scutellum pale ; meta- 

 thorax dark ; pleurte blackish ; halteres pale ; feet hairy ; coxa? 

 and base of the femora pale ; the tips of the latter brow^n ; tibiae 

 brownish tawny, infuscated at the tip ; the tarsi likewise. Abdo- 

 men blackish (often greenish in living specimens). Wings hya- 

 line, without any apparent stigma ; veins brown, costal and 

 auxiliary veins pale yellow ; the apical portion of the wings is 

 slightly pubescent along the middle of the cells. 



Hah. White Sulphur Springs, Ya. Twenty-one specimens 

 taken on the oOth of June, 1859. 



