104 PROCEEDINGS OF THE ACADEMY OF [1896. 



thorax without any yellow, except on collar above. Tarsi mostly 

 pale, in addition to the pale leg-markings of the 9 . Ends of mid- 

 dle tibite also pale. 



Abdomen without the two spots of the $ , but the distal margins 

 of the segments hyaline, with narrow dull yellowish bands, broadly 

 emarginate on each side proximally. 



Mut. $ , macxdata. — Hind margin of prothorax with two small 

 yellow marks. (One on Verbesina encelioides, Sept. 28th.) 



Mut. $ , cyanella. — Size small. Metathorax blue. (One on Hel- 

 iatithus annuiis, Sept. 21st). This agrees with true $ verbesince in 

 the dull front, orange flagellura, absence of spots on hind border of 

 prothorax, etc. 



Hab. — Las Cruces, N. M., abundant on flowers of Verbesina en- 

 celioides, Sept. 11th to 20th of October. On Sept. 28th, after wet 

 weather, they were freely copulating on the flowers. One had been 

 caught hy a Phymata. On Sept. 21st, a 9 of mut. intermedia and 

 the S mut. cyanella were taken on Helianthus annuus. 



69. Perdita albipennis Or.. Tr. Am. Ent. Soc, 1868, p. 386. $ (Hab., New 

 Mexico, Colorado). 



<?. Perdita hyalina Cr., Tr. Am. Ent. Soc, 1878, p. 68. (Hab., Colorado). 



The original type of albipennis was taken in 1867 by Dr. Samuel 

 Lewis, on a journey from Fort Wallace, Colo., to Fort Craig, N. M. 

 The types of hyalina were taken by Messrs. Ridings and Morrison. 

 In the latter part of July, 1895, I took the typical form, in both 

 sexes, on flowers of UeliaMJms annuus at La Junta, Colorado. The 

 males have the flagellum mostly orange, spots on hind margin of 

 prothorax, front shiny. P. hyalina is apparently a slight variety. 

 Var. helianthi. 



$ . — Differs from verbesince $ by its comparatively shining 

 front, blackish flagellum, and two spots on hind border of prothorax. 

 Differs from albijiennis $ by having the yellow marking on abdo- 

 men as in verbesince, and the dark flagellum. 



9 . — Abdomen striped as in albipennis, from which it is hardly 

 to be distinguished. In helianthi the stigma, when well colored, is 

 lemon-yellow, while in albipennis it becomes pale orange, and is 

 quite large. From verbesince, the 9 helianthi differs by its well- 

 striped abdomen, and the head is a little larger. 



The var. helianthi is occasionally taken (at least the 9 s) on Ver- 

 besina encelioides (Oct. 5th, etc.), at Las Cruces, N. M., but it is the 

 usual form in that locality on Helianthus annuus (Sept. 22d, etc.). 



