105 



tions stopped, and later I did not observe any specimens 

 in the night lodgings in the peach tree. 



58. Centris Brethesi, Schrottk. Moderately common, toge- 

 ther witii foregoing on Hojfmanseggia falcaria. 



59. Centris nigripes, Friese. Rare; together with the last 

 two species and on the same plant. I believe this to be a 

 variety of Centris lanipes, which, although not common, is 

 found in the district. 



60. Canephora apiformis, Friese. Generally distributed 

 round Pedregal. I have never found it except on the flowers 

 of Hoffmanseggia falcaria. Its flight resembles that of the 

 Centris species in speed, and it also has the peculiarity of 

 „Standing still" in the air in front of flowers, before diving 

 into them, just the same as Centris nigriventris. Feniales 

 much more numerous than males. A midsummer insect. 



61. Lithurgus laticeps, Friese. Rare in this district. It 

 Visits cactus flowers together with Ancyloscelis aterrima and 

 A. tricolor (see under these species). 



65. MegaChile anthidioides, Rad. j ^ ^^^^^ on several 



66. Megachile gomphrenae^,^^^ j ^^^^^.^^ ^^ ^^^^^.^ 



67. Megachile simillima, Sm. With respect to this species 

 I have only seen a few specimens, all on the flowers of the 

 European (here run wild) lancet-leafed thistle, Cirsium lan- 

 ceolatum, Scop, It has the peculiarity of burrowing into the 

 flowers, so that only a portion of the abdomen is visible. 



68. Megachile Jensen!, Friese. The commonest species 

 af Megachile in the Pedregal and Mendoza districts. Both 

 sexes could be met with throughout the whole midsummer. 

 I have never taken it on other plants than Hoffmanseggia 

 falcaria. 



69. Megachile argentina, Friese. Moderately common; 

 chiefly on Hoffmanseggia, although occasionally on other 

 plants, such as Cirsium lanceolatum. I have several times 

 found the cells, which are made up of cutting from various 

 leaves, of this bee a little under the surface of the ground. 



70. Megachile cylindrica, Friese. Very rare in the Men- 

 doza district. 



71. Megachile Jörgenseni, Friese. Together with M. argen- 

 tina on Hoffmanseggia and Cirsium. It resembles M. argen- 

 tina, but is abundantly distinct. 



73. Megachile tricincta, Friese. A beautiful and propor- 

 tionally robust species. Together with M. argentina and M. 

 Jörgenseni on the same plants. 



76. Megachile Hieronymi, Friese. Not rare, chiefly on 



