54 Journal of Entomology and Zoology 



bles tridentate, the teeth large; clypeus extremely densely punct- 

 ured; head with mixed white and black hair, the white conspicuous 

 at sides of face, the black especially abundant on lower half of 

 clypeus; antennae black; thorax above with creamy-white hair, with 

 black sparsely intermixed; metathorax with light and dark hair 

 mixed; pleura with black hair (no patch of light hair below) ; legs 

 black, with mainly black hair; tegulze black, with a green spot in 

 front; wings dilute brownish; b. n. meeting t. m.; first r. n. joining 

 second s. m. as far from base as length of first t. c. ; abciomen 

 shining, the first two segments with glistening white hair, the next 

 three with very thin light and ciark hair, the sixth appearing green- 

 ish (contrasting with the rich purple-blue of the fifth), and hoary 

 with appressed white hair; scopa black. 



Habitat: Claremont, California [Baker; Pomona coll. 182, 

 part) . Resembles O. pikci Ckll., but differs by the much more finely 

 punctured clypeus, the much shorter vertex, the much more closely 

 punctured abdomen, etc. 



The following key separates the above mentioned species of 

 Osiuia; all females with black ventral scopa. 



Hair of thorax above wholly or mainly black 1 



Hair of thorax above wholly or mainly Hght 3 



1. Very small, not quite 7 mm. long cyanosoma sp. n. 



Larger 2 



2. Tibice dark blue cyanopoda sp. n. 



Tibis black pogonigera Ckll. 



3. Small, about 7.5 mm. long melanopleiira sp. n. 



Larger 4 



4. Hair of thorax above all pale ochreous iiovomcxicana Ckll. 



Hair of thorax above with some dark intermixed 



nigroharhata sp. n. 



Nomada crotchii iiigrior Ckll. 



This was described from the female. The male (Claremont, 

 Baker) has no red on the thorax, but there are four small creamy- 

 white spots, two at the anterior corners of scutellum, and two on 

 postscutellum. Clypeus all cream-colored except upper edge; thirci 

 antennal joint little over half length of fourth; legs with more 



