40 ANDRENIDiE. 



of the second, and much narrower towards the marginal. Adaomen 

 petiolate in both sexes, in the males clavate. 



Of this genus three species are at present known, but the female 

 of the Mexican one only is described ; the form of the palpi separates 

 them from the genera previously established ; the maxillary palpi 

 are remarkable in having three stout joints and three slender ones. 

 In the neuration of the wings they agree with many other Halicti ; 

 but the clavate form of the abdomen at once distinguishes them. 



1. Cacosoma discolor, 



Female. Length 4 lines. — Black, with tints of green on the thorax, 

 and with the basal segment of the abdomen rufo-piceous. Head 

 with a thin hoary pile on the face ; opaque, with the clypeus shining 

 and having a few scattered punctures ; the apex of the flagellum 

 of the antennae fulvous. Thorax opaque, with the collar produced 

 laterally into an acute angular projection, which is bright green ; 

 the posterior margin of the mesothorax narrowly, and the base of 

 the metathorax bright metallic green, the latter with fine divergent 

 striae ; the wings hyaline, iridescent, and with the anterior margin 

 of the fore wings bordered with fuscous ; legs rufo-piceous, their 

 pubescence pale and glittering. Abdomen opaque and subpetiolate .;' 

 the basal segment with a black band in the middle, and the pos- 

 terior margin narrowly black ; the basal margin of the third seg- 

 ment narrowly green ; the margins of the segments beneath fringed 

 with pale pubescence. 



Male. Length 4 lines. — More slender than the female. The sides 

 of the face and the clypeus green ; antennae fulvous, slightly fus- 

 cous above. Thorax, legs, and wings as in the female, the fuscous 

 border of the latter commencing in the marginal cell. Abdomen 

 with the two basal segments rufo-testaceous ; the basal margin of 

 the third slightly green. 



Hah. Mexico, Oajaca. 



2. Cacosoma abdominale. 



Male. Length 4^ lines.' — Head and thorax brassy green, abdomen 

 ferruginous. The face with pale fulvous pubescence ; the clypeus 

 produced ; the flagellum of the antennae fulvous beneath, above 

 fuscous, the joints subarcuate. The mesothorax of a brassy green ; 

 the metathorax dark green, and rugose at the base; the pubes- 

 cence pale fulvous ; wings hyaline and iridescent, the nervures 

 pale ferruginous ; the tips of the femora, the tibiae, and tarsi pale 

 ferruginous. Abdomen smooth, shining, and ferruginous. 



Bob. Chili. 



3. Cacosoma agile. 



Male. Length 4| lines. — Head and thorax green ; abdomen pitchy 



