species ^ 



I lis 



266 S. W. WILLISTON, M. D. 



5. Eed or yellowish species ; front with a more or less pronounced obtuse an- 



teuniferous projection marked with a round black spot; front of female 

 narrow above, the ocelli rather remote from the vertex ; mesouotum 

 (except the sides) in ground color black, concealed beneath dense ochra- 

 ceous pollen, leaving more or less apparent black stripes; legs yellow, 



the hind femora or tibiie more or less brownish or blackish 6. 



Not such species; black or blackish 9. 



6. Three antennal joints of nearly equal length ; front tarsi of female notice- 



ably widened conjuucta. 



First two antennal joints short 7. 



7. Third and fourth abdominal segments with slender yellow stripes 8. 



Third and fourth abdominal segments with slender spots in the shape of a 



rectangular V placiva n. sp. 



8. Black stripes of mesonotum conspicuous; wings broad, brownish yellow. 



pliseoptera. 

 Black stripes inconspicuous, mostly concealed beneath light pollen ; smaller 



f Iivi<la. 

 lavipeiiiiis. 



9. Wings hyaline, except the immediate base; hind femora and tibite black 



ciliate; penultimate joints of hind tarsi white; front tarsi of female 



dilated pilipes. 



Not snch species 10. 



10. Face projecting, yellow with a black stripe ; wings hyaline with the subcostal 



(and costal %) cells clouded clavata. 



Face not projecting, wings more or less extensively brown 11. 



11. Hind tarsi, except base of metatarsi, white 12. 



Hind tarsi not white 13. 



12. Abdomen broadly spatulate distally clarapex. 



Abdomen not broadly spatulate distally ; the whole apex of the wings iu both 



sexes hyaline ; smaller species sp. 40. 



13. Thorax deep blue sp. 



Thorax black; third and fourth abdominal segments each with four oval 



yellow dots, in two pairs, the anterior pair remote, the posterior pair ap- 

 proximate adspersa. 



27. Bacclia steiiogaster n. sp. 



% . — Length 7 — 8 mm. Frontal triangle metallic, blackish blue, finely rugose. 

 Face of the same color, thinly dusted, on the sides and below yellowish. An- 

 tennjE yellowish red, third joint short, yellowish red. Mesouotum metallic 

 bronze black, in front with two pollinose stripes. Pleurae largely obscurely yel- 

 lowish. Abdomen very slender ; shining black ; first segment on the sides, the 

 second and third with a basal band and one just beyond the middle, fourth seg- 

 ment at the base, yellow. Wings short and small ; hyaline, the costal cell, beyond 

 the tip of auxiliary, brownish yellow; third vein nearly straight, terminating 

 at the tip of the wing; last section of fourth vein /shaped, terminating rectan- 

 gularly.- Legs yellow, the hind metatarsi a little thickened. 



Two specimens, Chapada. The species is allied to brevipennis and 

 riigosifroHs Scliiner, but differs in the color of the legs and markings 



