102 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



gites 1-6, first interrupted more or less widely and usually narrowed 

 somewhat toward the midline, remaining fasciae continuous though 

 somewhat constricted at the dorsal midline, their borders sinuate 

 especially the anterior, apex of seventh tergite, posterior lateral spots 

 on sternites 2-6, femora more or less distally and below, tibiae except 

 below on first pair, and tarsi, greenish yellow. The yellow on the legs 

 lacks the greenish tinge. 



The pubescence on the head, thorax, base of abdomen, and the 

 basal joints of the legs is white and unusually well developed. Seg- 

 ments 7 and 8 of the flagellum are distinctly spinose on the posterior 

 surface and on many specimens also 6 and 9, but less evidently so. 

 The intermediate femora are dentate below. The second sternite 

 bears a median, longitudinal process and the sixth a smaller, narrow, 

 pointed process. 



Female. — Black: Clypeus, labrum, mandibles except tips, scape 

 below, spot between antennae, frequently united with spot below 

 anterior ocellus, anterior orbits, posterior orbits, posterior border of 

 prothorax almost wholly, tegulae, narrow lateral lines on scutum, 

 lateral spots on scutellum usually connected by a more or less evident 

 line at posterior border of scutellum, fascia on metanotum, sometimes 

 suppressed, spot on sides of median segment, spot on metapleurae, 

 small posterior and larger anterior spot on mesopleurae, broad fasciae 

 on tergites 1-5, first narrowly interrupted medially, remainder con- 

 tinuous, each biemarginate on anterior dorsal border, deep and evi- 

 dent on second and third, more wide and shallow on fourth and fifth, 

 all with an acute emargination at the middle on posterior border, 

 lateral spots on sternites 2-4, frequently connected by very narrow 

 apical lines, femora distally more or less, tibiae except line below, and 

 tarsi, greenish white or yellow. The markings on the thorax, median 

 segment, and legs are yellow, elsewhere greenish white. 



Length. — 13-17 mm. 



The pubescence is white and conspicuous but not so well developed 

 as on the male. The flagellum is light on the lower surface, testa- 

 ceous on the male, yellowish on the female. On most specimens the 

 sixth tergite of the female is black; on some it is maculated and on 

 some of these the dorsum of the median segment is also maculated. 

 It is difficult to distinguish the less extensively maculated females of 

 this species from the most extensively marked forms of spinolae, and 

 likewise in many cases it is hard to separate the males from the males 

 of similans. 



Habitat. — Colorado, Idaho, Washington, Vancouver, California, 

 New Mexico, and Texas. 



Number of specimens examined. — Males, 39; females, 28. 



