1893.] NATURAL SCIENCES OF PHILADELPHIA. 505 



Form usually slender and only feebly clothed with pubescence, 

 never bee-like as are the typical species of the genus Tachytes; man- 

 dibles distinctly emarginate (in outer side, bidentate within, their 

 apices simple ; antennae on the average more slender than in Tachytes ; 

 eyes converging towards the vertex ; ocelli lying on a swelling, the 

 anterior is round and distinct, the posteriors reniform and placed 

 obliquely ; front never raised along the inner eye-margins; face bituber- 

 culate behind antenna' ; collar not reaching the level of thedorsulum; 

 on the last dorsal abdominal segment is a well developed pygidium 

 in the 9 , which is scarcely developed in the S , and is entirely naked 

 in both sexes ; the median cell of the hind wings reaches proportion- 

 ately not as far towards the apex of wing as it does in Tachytes; the cu- 

 bital vein originates behind the apex of the submedian cell ; tibia? and 

 tarsi spinose ; tarsal comb of ? very long and flexible; fore femora 

 of $ at base distinctly emarginate ; middle tibia? with one spur ; fore 

 tibice on outer side spinose; last ventral plate of $ emarginate. Size 

 variable. 



This genus is well represented in the United States as it is also in 

 Europe. Those of our species heretofore described have in every 

 case been referred to the genus La era. The form of the hind ocelli 

 will distinguish it most effectually from Ancistromma and Tachytes. 



FEMALES. 



1 — Space between the eyes at top less than the length of antennal 

 joints 2 and 8 united. 

 Metathorax above granulated; femora and tibia? entirely black. 



Length 12 mm amplus. 



Metathorax above strongly reticulated; legs almost entirely red. 



Length about 9 mm Belfragei. 



Space between eyes at top about equal to length of antennal 



joints 2 and 3 united 2 



Space between eyes at top greater than the length of antennal 



joints 2 and 3 united 11 



2 — Metathorax strongly reticulated above; abdomen entirely red . . 



texanus. 



Metathorax coarsely wrinkled above; abdomen about equally red 



and black quebecensis. 



Metathorax not strongly reticulated or wrinkled above, at the 



most finely granulated or striated 3 



3 — Hind legs reddish (anterior margin of clypeus rounded out). 

 Pygidial area about two-and-a-half times longer than it is broad at 

 the base; tarsi armed with spines at apex of joints only .... 



Ashmeadii. 



Pygidial area not more than twice as long as it is broad at 

 33 



