354 PROCEEDINGS OF THE ACADEMY OF [1897. 



tures; vertex shining, microscopically sculptured with very sparse 

 punctures. Mesothorax sparsely punctured ; tubercles, aud hind 

 border of prothorax, more or less pale dull yellowish ; sometimes 

 this is hardly noticeable. Tegulae hyaline with a blackish spot ; 

 wings hyaline, stigma and nervnres white; stigma loug and well- 

 formed, marginal cell with its post-stigmatal portion longest, 

 squarely truncate at end, with a very fine appendicular nervure. 

 Secoud submarginal high, narrowed rather more than half to mar- 

 ginal; third discoidal distinct. Anterior tibioz and tarsi wholly 

 lemon-yellow, anterior femora yellow suffused with brown ; middle 

 tarsi whitish ; middle and hind femora and tibia?, and hind tarsi, 

 piceous ; the middle femora in front, and the middle and hind 

 knees, dull yellowish or whitish ; middle femora angled below. 

 Abdomen pale brown, the hind margins of the segments hyaline, 

 the venter dull brownish-orange. 



9 . Same size and form. Face wholly dark, except that the up- 

 per edge of the clypeus is dull whitish, this coloration very incon- 

 spicuous. Head not so large, transversely oval ; antennae shorter. 

 Scape black, flagellum dull broivnish-orange, infuscated at the base. 

 Legs piceous, anterior tibiae and tarsi obscurely dull yellow in front. 

 Abdomen piceous above and below, without markings. 



Hab. — Mesilla, New Mexico, June 7th and 9, 1897, on flowers of 

 Sida hederacea. They fly actively about the flowers, and in dull 

 weather I found the males at rest in the flowers. Six males were 

 taken, but only one 9 • 



P. sidaz S runs in my table of Perdita (Proc. Phila. Acad., 1896) 

 to the neighborhood of P. semicrocea, but it cannot be confused 

 with anything described, if attention is paid to the characters italic- 

 ized above. The 9 is equally distinct. In the shape of the head, 

 and the sexual difference in the color of the abdomen, P. sidaz re- 

 calls P. latior, but the marginal cell is entirely different. On June 

 7th, I took a single 9 of P. latior in a flower of Sida hederacea in 

 Mesilla ; it had probably wandered from an adjacent Sphozralcea, 

 as renewed search discovered no more of them. 



Perdita callicerata Ckll. 



9. Larger than the S, length about 5} mm., clypeus entirely 

 cream color, with the usual two black specks; lateral face-marks 

 transversely subreniforin, white, extending about as high as level of 

 top of clypeus ; antennae as in $ ; mesothorax darker and bluer ; legs 

 virtually as in $ ; lateral light marks of abdomen larger and squarer. 



