AMERICAN HYMENOPTERA. 193 



OPAMDRESfA gu. nov. (Type Andrena cressonii Rob.). 



FEMALES. 



Abdomen closely, evenly, rather strongly punctured, segments 2-4 whitish fasci- 



ate ; process small ; enclosure short cressonii. 



Abdomen impuuctate or nearly so 1. 



1. Length 6-7 mm., abdomen greenish 3. 



Length 8-9 mm., abdomen black 2. 



2. Clypens smooth, shining and impunctate, except on the sides ; enclosure finely 



rugose, ex(;ept basal middle bipunctata. 



Clypeus finely rugose, opake ; enclosure rather strongly rugose- .robertsonii. 



3. Fovea narrov? ; clypeus bare, convex, metallic; enclosure rugose ; cell III5 long. 



personata. 



Fovea broad ; clypeus more pubescent, flatter, not metallic ; enclosure less 



rugose ; cell III5 shorter ziziee. 



MALES. 



Abdomen impunctate or nearly so 2. 



Abdomen closely, evenly, rather strongly punctured, apical ventral process linear; 

 enclosure short ; face marks pale yellowish 1. 



1. Joint 3 = 4-|-5; apical middle of clypeus black; lateral face marks large, 



subquadrate cressonii. 



Joint 3 = 5; entire apical margin of clypeus black; lateral face marks sub- 

 triangular, rather small, sometimes wanting dubla. 



2. Face marks whitish ; abdomen greenish ; the smallest species 4. 



Face marks yellow ; abdomen black ; joint 3^5 3. 



3. Cheek narrow, (;onvex, regularly rounded ; enclosure unusually broad and 



rough ; abdomen finely, sparsely punctate ; angles of ventral segment 



6 reflexed ; clypeus yellow robertsonii. 



Cheek broad, flat, subtriangular, with a rounded angle behind middle of eye ; 

 enclosure small, finely rugose, except basal middle; abdomen almost 

 impunctate; clypeus. and sometimes spot on each side of face, yellow. 



bipunctata. 



4. Antenna short, joint 3 nearly = 4 + 5 ; clypeus rather flat, whitish ; sometimes 



a whitish dot on each side of face zizise. 



Antenna long, joint 3 no longer than 4; clypeus convex, whitish, as well as a 

 spot on each side of face personata. 



PTERAKDRKNA gn. nov. (Type Andrena pulchella Rob.). 



FEMALES. 



Stigma more than one-half width of cell III1+2 3. 



Stigma less than one-half width of cell 1+2 1. 



1. Face with a large yellow spot on each side; cheek nearly as broHd behind 

 summit of eye as elsewhere; pubescence rather dense, fulvous; abdo- 

 men distinctly punctate, shining, broad apical margins of segments 



pale testaceous pulchella. 



Face without yellow marks- • > 2. 



TRANS. AM. ENT. SOC, XXVIII. (25) JUNE, 1902 



