1903.] NATURAL SCIENCES OF PHILADELPHIA. 607 



questionable that I believe lea.st confusion will occur if it goes for the 

 present under another name. It may be called A^. armatella, sp. n. 



There is a second species in Canada (Baker coll., No. 2,174, in Na- 

 tional Museum) which I had at first confused with N. armatella; the 

 male is about 10 mm. long;, and differs from armatella thus : 



N. hethunei, sp. n. 



Denticle rudimentary. 

 Posterior orbits broadly red. 



Metathorax with four red spots. 

 Basal nervure very little basad. 



Band Ijroadly interrupted. 



N. armatella, sp. n. 



Denticle on labrum evident. 



Posterior orbits black. 



Front and vertex black ; a red spot j Front and vertex largely red 

 above each eye. I 



Scape cylindrical. I Scape swollen. 



Third antennal joint longer than Third joint broader than long, 

 broad. 



Pleura with hardly any red. ] Pleura with much red. 



Base of metathorax coarsely ivrin- | Base of metathorax rugulose. 

 kled. 



i\Ietathorax entirely black. 



Basal nervure considerably basad 

 of transverso-medial. 



Yellow band on second abdominal 

 segment with only a linear inter- 

 ruption. I 



Apical plate very narrow. I Apiccd plate very broad. 



The characters italicized are important; the others may not have 

 specific value. A'', hethunei is named after the Rev. C. J. S. Bethune. 



Another species with a denticle on the labrum is N. depressa, Cresson, 

 if I have correctly identified as such a specimen collected by Mr. 

 Viereck at Lehigh Gap, Pa., June 30, 1897. It is a female, and has the 

 large semilunar depression on the fifth abdominal segment as described 

 in depressa. It is about 9 mm. long. The second transverso-cubital 

 nervure is incomplete in both wings. An allied species, described 

 below, occurs in Oregon. 



Two males collected bj^ ]\Ir. ^^iereck at Philadelphia, Pa., May 2, 

 1897, have the mesothorax marked wdth dark red just as in N. arma- 

 tella, and also possess a very rudimentary spine on the labrum, only 

 visible because of its reddish color. I was almost ready to think these 

 a varietal form of armatella, until I o])served that they had bidentate 

 mandibles, and belonged to Gnathias. As a matter of fact, they are a 

 varietal form of N. hella, parallel to the variety of A'^. perplexa cited in 

 the table of Gnathias. Typical hella also has a minute spine on the 

 labrum, or rather a rudiment of a spine. 



Nomada volatilis, Smith, described from Canada, is, I believe, a form 

 of N. hella. We are not informed whether it has bidentate mandibles, 



