64 PEOCEEDINGS OF THE ACADEMY OF [1896. 



(3). That there is only one species, larrece, marcialis being the 

 dimorphic $ and /arreor»9?i the normal $ of the same. 



While I incline to one of the latter suppositions, the difference 

 between the three forms is very great, so that ia the absence of 

 further evidence they must be provisionally regarded as species. 



18. Perdita semicaerulea n. sp. 



9 . — Length 6 mm. Unusually hairy, the pubescence erect and 

 white. Head of ordinary size, dark greenish-blue, bluer at sides of 

 face, more brassy-green between antennre. Vertex finely rugulose, 

 punctured. Clypeus high, pitch-black, smooth with large moder- 

 ately close punctures. The only face-markings consist of a shining, 

 hairless, bright sulphur-yellow oval patch on each side of the clypeus, 

 separated from the eye margin by a distance at least equal to its 

 own diameter. 



Antennse dark-brown, scape black, last joint of flagellum becom- 

 ing pale. The antennse are rather conspicuously enlarged toward 

 their ends. 



Mesothorax and scutellum smooth and shining, but with deep, 

 large and rather close punctures. Thorax all black, except the 

 metathorax which is l)lue. Pleura with quite long white hairs. 



Tegulse hyaline. Wings milky-hyaline, stigma very pale yellow, 

 hyaline in middle, nervures colorless, costal uervure black. Marginal 

 cell rather short, appendiculate, poststigmatal portion hardly longer 

 than'substigmatal. Second submarginal large, narrowed about one- 

 half to marginal. Third discoidal distinct. 



Legs brown-black, a little yellow on anterior tibipe and knees. 



Abdomen shining, brown-black above and beneath. Sides of 

 first segment, and in a less degree those of the others, with tufts of 

 white hairs. Dorsum of last three segments more or less hairy, that 

 of the last one considerably so. 



Hab. — San Marcial, N. M., on Larrea, at the same time and place 

 as P. larrece. One specimen. (Ckll., 3,077). This species is easily 

 recognized by the dark clypeus, with a shining, smooth, yellow spot 

 on each side of it. It is not nearly related to P. larrece, but rather 

 to P. phymake, which, however, has not the yellow spots. 



A species uith the end of the abdomen rufou.'<, found on Croton. 



19. Perdita crotonis n. sp. 



9 . — About 5 mm. long. Head rather broad, shining, dark blue 

 or greenish-blue ; clypeus except two black dots, a transversely 



