SOUTH amp:rican diptera. 269 



35. Baeclia placiva n. sp. 



% 9 • — Length 11 mm. Structure aud coloration of head, thorax and legs as 

 in B. phxoptera. Abdomen, male : first segment yellow with a blackish brown 

 cross band ; second segment elongate, cylindrical, but little widened distally ; in 

 color reddish yellow with the distal end blackish ; third segment nearly as broad 

 as the thorax distally, brownish black with two oblique reddish stripes, in the 

 form of a V, separated by a linear space in front aud running into the posterior 

 margin behind ; fourth segment a little broader than long, with the same color 

 and markings as the third, and (apparently) a yellow longitudinal stripe on each 

 side. In the female the second segment is nearly as slender as in the male, the 

 three following segments with a V-shaped marking as in the male aud a lateral 

 longitudinal stripe or margin. Wings yellowish brown in front, the costal cell 

 yellow; behind broadly grayish hyaline; third longitudinal vein with a deep 

 sinuosity into the first posterior cell, almost as in species of Didea. 



Two specinieiLs, Chapuda. 



36. Bacclia sp. 



A single injured female speeiiDen, belonging in the group with the 

 foregoing, has the costal aud marginal cells yellow, and the subcostal 

 brown, the rest of the wing hyaline ; the abdomen is not broad, and 

 not cylindrical basally, the second segment but little longer than the 

 third and not twice as long as its greatest width ; the second segment 

 with two yellow and two brown bands, the third, fourth and fifth 

 each with the anterior border and anterior lateral yellow and two 

 oval obli([ue yellow spots, connected or not with the yellow margin 

 in front. Length 11 mm. 



37. Bacclia pilipes Schiner. 



Three specimens, male and female, CIui|)ada. The identification 

 is not at all doubtful, though Schiner leaves it to be inferred that the 

 abdomen is shining black, wdiereas it is deep opaque black ; the parts 

 he describes as reddish yellow in these s])ecimens are more metallic 

 blue. The last two joints of the hind tarsi are brown. 



38. Baccha adspersa Wied. 

 Numerous specimens, Chapada. 



39. Baccha clarapex Wied. {Syrphus). 



Wiedemann's description leaves no- doubt of the correctness of the 

 determination of numerous specimens from Chapada aud Uarcarizal, 

 though to no one will it fully a})ply. In almost every case the frontal 

 triangle and the median portion of the face is shining steel-blue, not 

 black ; in only one or two specimens the yellow spots of the abdo- 

 men are as he describes them ; in most ca.ses there is an additional 



