226 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io9 



Mesopleuron dorsally with distinct broad brown stripe, continued on ptero- 

 pleuron; spots on wing smaller, and apex of wing clear, the second and 

 third veins not with brown clouds about their apices; antenna with at least 

 a distinct, wedge-shaped black spot anterodorsally on third segment; 

 smaller species, the body and wing each 2.5-4 mm 4 



4. Hind crossvein narrowly and indistinctly, or not at all, infuscated, the fore 



crossvein only weakly so 3. O. boletina (Zetterstedt) 



Both crossveins broadly and heavily infuscated, that on the hind crossvein 

 usually broadening midway 5 



5. Antennal segments 1 and 2 entirely yellow; upper orbit, between posterior 



orbital and the vertical bristles, usually with a few short black hairs on 



outer half 4. O. betulae, new species 



Antennal segments 1 and 2, or at least the first, entirely or chiefly black; 

 upper orbit bare of hairs 5. O. meijerei Collin 



6. Wing pattern reticulate (fig. 6); face entirely yellow in ground color; second 



antennal segment yellow, rounded dorsally 6. O. picta (Loew) 



Wing with numerous black or black-brown spots, most of them surrounded 

 by a whitish corona (figs. 7-9); face broadly black to brown on upper two- 

 fifths to half, from eye to eye; second antennal segment narrowly com- 

 pressed and whitish on dorsal third to two-fifths 7 



7. Vibrissa and one or two adjacent oral bristles distinctly flattened, the vi- 



brissa broadly so on basal half 7. O. williamsi Johnson 



Vibrissa and adjacent bristles slender, not unusually broadly flattened. ... 8 



8. Wing spots large and dark (fig. 8) ; second and third antennal segments each 



with large black mark on outer surface, and at least the third equally 

 dark on most of inner surface; front relatively broad, obviously broader 

 than long, and approximately twice the width of an eye; mesonotum 



without posteriorly bifurcate brown stripe 8. O. coronata, new species 



Spots on wing small and pale (fig. 9); antennal segments almost entirely 

 yellow; front relatively narrow, approximately square, and 1.4-1.5 times 

 the width of an eye; mesonotum with narrow median brown stripe, pos- 

 teriorly bifurcate, each half ending in a large brown spot beside fourth 

 dorsocentral bristle 9. O. parvipunctata, new species 



i. Odinia biguttata, new species 



Species with two evenly spaced black spots in marginal cell. 



Male. Unknown. 



Female. Gray-black, heavily pollinose species; frontalia black, 

 contrasting with the bright gray orbits and small frontal triangle, 

 the ocellar tubercle and a spot about the base of each bristle sub- 

 shining brown; narrow anterior margin of front, lunule, upper face 

 and palpi yellow, the lower half of face and the cheek silvery white 

 on yellow ground color; antenna yellow except for small fuscous spot 

 on outside of second segment and small fuscous spots on inside and 

 outside of third segment; arista yellow at base, the rest black; vi- 

 brissa, oral bristles, and postgenal hairs yellow to whitish yellow, all 

 dorsal bristles black, but the anterior pair or two of orbital bristles i 

 yellowish distaUy. Thorax predominantly gray-black, the humeri i 

 and disk of scutellum yellowish ; bristles and most of hairs set in i 

 shining brown spots; mesonotum anteriorly with narrow median 



