404 Dr. A. S. Packard; JVs Revision of the 



9 . Differs in its more cubical head, which is still much less so than 

 in Psen, its more clavate antenna?, less elevated vertex and clypeus, and 

 a little shorter abdomen than usual, the tip of which has a broad spatu- 

 late flattened supraanal area. 



All the species have reddish antennae, and the base of the abdomen 

 is broadly banded with red, and the feet are pale reddish. 



The genus differs from Psen by its broader and shorter head, longer 

 body, much more clavate antenna?, the much longer propodeutn and ab- 

 domen, and the 9 tip is broad and flattened, where in Psen there is 

 a linear narrow groove. The 2d subcostal (cubital) cell varies greatly 

 both in Psen and the present genus, and but little reliance, aside 

 from the other characters enumerated above, can be placed in it. 



Synopsis of the Species. 



A. 2d — 3d Abdominal rings red. 



9 • Antenna red, black stripe above; front silvery. ..M. argentifrons, Cress. 



9. Antennae black above, red beneath; front golden. .M. Cressonii, Pack. 



9 • 2 basal abdominal rings red only on hind margin. ..M. basirufa, Pack. 



£ . 2 basal abdominal rings red, denticulated M. denticulata, Pack. 



% . 2 basal abdominal rings very long, pale red, tip red 



beneath, sub-denticulated M. monticola, Pack. 



Q. Pedicel of abdomen very short, half as long as 

 abdomen is wide, projaodeurn very finely stri- 

 ated M. proxima, Cress. 



B. Part of one abdominal ring red. Antennae red at tip, front 



silvery, abdomen very long, pedicel usually as long as the ab- 

 domen is wide. 

 %. Body shorter than usual, pedicel shorter than 



abdomen is wide M. borealis, Smith. 



^ . Antennce very clavate, with a narrow red ring, pe- 

 dicel half as long as abdomen is broad M. singuluta, Pack. 



•t, . Two-thirds of the 3d abdominal ring red; abdo- 

 men very long, sutures well defined, cylindrical, 

 twice as long as rest of the body M. unicincta, Cress. 



Mimesa argentifrons Cresson. 



31. argentifrons Cresson, Proc. Ent. Soc. Phil., June, I860, p. 4S7. 



Col. Terr. ; Illinois. (Coll. Ent, Soc. Phil.) 



Some specimens from Illinois are a little smaller, autennne much 

 darker, propodeum not so coarsely marked as usual; they also differ from 

 the Colorado specimens in having the 4th joint of abdomen two- 

 thirds black, where in the types from Colorado only the posterior one- 

 quarter is black. 



