REVISION OF STKEPSIPTERA PIERCE. 35 



None of the other salient alterations found by Perez could be ex- 

 pected in this species because of the close resemblance of the two 

 sexes. Andrena crawfordi is a very generalized bee. 



The left wing of the only parasitized specimen of Andrena advarians 

 in the writer's collection has a spurious nervure in the third discoidal 

 cell. Whether due to parasitism or not, such an aberration is of 

 interest. The results of wing examination in Andrena crawfordi 

 would lend credence to the assumption that parasitism does affect the 

 tracheation of the wings. A larger series is necessary to prove this point. 

 Mr. Crawford has furnished the following list of Andrena which are 

 known to lack the second transverse cubital vein at times. It would 

 be interesting to know whether parasitism was invariably the cause. 

 Andrena arabis Robertson. 



crawfordi Viereck. — A known stylopized species. 

 geranii Robertson. 



illinoiensis Robertson. — A known stylopized species. 

 platyparia Robertson. 

 Opandrena bipunctata Cresson. — A known stylopized species. 

 personata Robertson. 



robertsonii Dalla Torre. — A known stylopized species. 

 Pterandrena asteris Robertson. 

 l-rigiana Robertson. 



solidaginis Robertson. — A known stylopized species. 

 Trachandrena claytonix Robertson. — A known stylopized species. 

 forbesii Robertson. 

 Tiippotes Robertson. — A known stylopized species. 



6. Synonymy due to stylopization. 



Stylopization may so change a species that it can not be identified 

 unless one understands the direction of the changes under such con- 

 ditions. A stylopized male or female is a male recovering the char- 

 acters of the female, or a female borrowing the attributes of the male 

 (Perez, 1886). 



Notable examples of forms based on stylopized individuals are: 



Andrena afzeliella (stylopized) convexiuscula Kirby. 



Andrena nigrosenea (stylopized) aprilina Smith. 



Andrena, sp. ? (stylopized) picicrus Schenck. 



Andrena solidula (stylopized) junonia Viereck. 



Andrena subtilis (stylopized) angustitarsata Viereck. 



Andrena tibialis (stylopized) movffetella Kirby. 



Andrena trimmerana (stylopized) picicomis Kirby. 



Andrena trimmerana (stylopized) picipes Kirby. 



Prosopis rubicola (stylopized) versicolor Saunders. 

 It is very probable that most of the complicated synonomy in 

 Andrena in Europe is due to stylopization. 



