185 



THE NORTH AMERICAN BEES of the GENUS PROSAPIS. 

 By T. D. A. Cockerell, N. M. Agr. Exp. Sta. 



The genus Prosapis (or Prosopis) consists of small bees with 

 almost naked bodies, more resembling the Pemphredonidse in 

 appearance than their allies among the Andrenidre. 265 species 

 are known, the genus being of world-wide distribution. Our 

 species never exhibit metallic colours, but some from Australia 

 (e. g. P. cognata, Sm., P. purpurata, Sm.) show blue and purple. 

 In certain species the base of the abdomen is ferruginous ; this 

 is the case with our own P. nelambonis, Rob., and P. flammipcs, 

 Rob., from the Eastern U. S. (Illinois, Florida), but it is not 

 observed in any of those found west of the Mississippi. The red 

 base of the abdomen reappears, however, in the Sandwich 

 Islands species, P. hilaris, Sm., and P. volatilis, Sm. The 

 extreme development of the red is reached in the Australian 

 P. rubricata, Sm., which is red with yellow markings, the scu- 

 tellum, metathorax, pectus, and legs black. 



Several species found in Mexico show more or less yellow 

 on the scutellum, a character not seen in those inhabiting the 

 United States. This fact is interesting, because in Perdita a 

 Mexican species (P. mexicanorum, Ckll.) has a yellow post- 

 scutellum, while all of the United States species have , this 

 part dark. 



The sexes differ considerably in the markings, and the males 

 present the best distinctive characters. The following table 

 may be used to distinguish the known North American species 

 in that sex : — 



Males. 



1. Supra-clypeal mark entirely absent . nevaclensis ; also schwarzii. 



2. Supra-clypeal mark present 3. 



3. Scutellum with more or less yellow ; species of 



Mexico ........ 4. 



Scutellum without any yellow . . . . 7. 



4. Abdomen with two entire narrow white bands . 5. 

 Abdomen without entire white bands ... 6. 



5. Markings white ; 2nd segment of abdomen very 



coarsely punctured ...... grossa. 



Markings yellow ; 2nd segment of abdomen more 

 finely punctured ....... maculipennis. 



6. Abdomen very minutely sculptured .... dubiosa. 

 Abdomen with 1st segment presenting large deep 



punctures ........ mexicana. 



7. Large species with the scape heart-shaped, half 



light, half dark, and the tubercles wholly dark ; 

 lateral face-marks broadly triangular . . . basalts. 

 Not so 8. 



