580 PROCEEDINGS OF THE ACADEMY OF [Aug., 



NORTH AMERICAN BEES OF THE GENUS NOMADA. 

 BY T, D, A. COCKERELL. 



Nomada superba, Cresson, var. a. 



(J'. — Smaller (about 10 mm. long) ; basal nervure meeting transverso- 

 medialj but on the basad side; lateral face-marks truncate above, 

 but sending beyond a fine line to top of eye; lower part of posterior 

 orbits with a yellow stripe. 



Hab. — Cheyenne, Wyoming, June 15 (collection C. V. Riley); one 

 in U. S. National Museum, If the characters are constant in the lo- 

 cality (which is quite a new one for the species) this may be a valid 

 subspecies. 



The following species more or less resemble Nomada luteola, and may 

 be conveniently treated together: 



Males. 



All have scape yellow in front ; mesothorax black ; abdomen with yel- 

 low^ bands, that on second segment entire or interrupted by a 

 line only. 



1. Scutellum all black ; tegulse testaceous ; supraclypeal mark absent ; 



flagellum bright ferruginous beneath, not denticulate; band on 

 first segment broadly interrupted; bands on second and third 



with a linear interruption, dentarice, Rob. 



vScutellum yellow or spotted with yellow 2. 



2. Transverse medial nervure a little basad of basal ; third antennal 



joint not over (rather less than) half length of fourth; postscu- 



tellum and metathorax wholly black (Cahfornia), 



sanctcecriicis, Ckll. 

 Basal nervure meeting transverso-medial ; postscutellum largely 



or wholly yellow, 3. 



Basal nervure ending distinctly (often greatly) basad of transverse 



medial, 5. 



3. Metathorax all black, scape very stout (Washington State), 



pascoensis, Ckll. 



Metathorax with much yellow; face narrow, facial quadrangle 



longer than broad, not narrowed below, 4. 



4. Mesothorax wholly black; apex of abdomen entire . vinda, Say. 

 Mesothorax with lateral margins yellow; apex of abdomen very 



faintly notched, zehrata, Cress. 



