540 PROCEEDINGS OF THE ACADEMY OF [1893. 



Produced portion of anterior margin of clypeus strongly bidentate 



vertex with a few, large, scattered punctures; first joint of flag- 



ellurn less than one-third longer than the second .... Sayi. 



5 — Pygidial area long, narrow, its length a little more than twice 



greater thau its width at base; wing-stigma black or dark-red. 



bicolor. 



Pygidial area of a more triangular form, its length not more than 

 twice greater than its base is broad; wing-stigma yellowish.. . 



pygidialis. 



6 — Metanotum with a well-marked, triangular depression at apex; 

 the length of the marginal cell fully equal to that of the first 

 subrnarginal; entirely black, the pubescence of thorax white . 



occidentalis. 



Metanotum without a well-marked depression at apex (if at all 

 present it is very indistinct); length of marginal cell a little less 

 than that of the first subrnarginal; abdomen black and red, or 

 entirely black, the pubescence of thorax usually black, though 



sometimes w T hite nubeculus. 



7 — Metanotum with coarse, irregular, radiating striatums; antenna? 



and legs stout nevadieus 



Metanotum finely sculptured 8 



8 — Metanotum finely granulated; teguhe testaceous 9 



Metanotum very finely striated; tegulse whitish elegans. 



9 — Produced portion of anterior margin of clypeus narrow, elongate, 

 truncate at apex; meso-and metapleura? finely sculptured. . . 



montanus. 



Produced portion of anterior margin of clypeus armed with three 

 large teeth; meso-and metapleurae very coarsely sculptured . . 

 asper. 



MALES. 



1 — Marginal cell as long or longer than the first subrnarginal (if 



shorter it is scarcely noticeable) 2 



Marginal always distinctly shorter than the first subrnarginal . 7 



2— Entirely black 3 



More or less red 5 



3 — Pubescence of thorax black ; fore-wings, except basal third, fus- 

 cous; metanotum strongly reticulated. nubeculus (=^iigripilosvts) 



Pubescence of thorax white 4 



4 — Wings hyaline throughout ; first joint of flagellum fully one- 

 third longer than the second ; metanotum not depressed . . . 



unlcolor. 



Fore wings stained fuscous medially ; first joint of flagellum 

 about one-quarter longer than the second ; metanotum more or 



less depressed before apex occidentalis. 



5 — Pubescence of thorax white ; metanotum reticulated 6 



Pubescence of thorax black nub' cuius. 



