268 S. W. WILLISTON, M. D. 



the next. The color of the wings is us in phceoptera, but the thorax 

 is like that of livida, and the wings in breadth seem intermediate 

 between the two. 



32. Bacclia livida Schiner. 



Numerous specimens, Chapada. Both males and females among 

 themselves differ very materially in size, but I cannot distinguish them 

 specifically. The abdomen among the females differs very materially 

 in the shape of the second segment, and all those in which it is broad 

 ♦seem to have the front somewhat l)roader above. Bacclia lineata 

 Macq. seems to be an allied species. 



33. Bacclia n. sp. 



Several closely allied specimens differ from plucoptera and livida in 

 the wings being nearly hyaline, with the costal and subcostal cells 

 yellow ; in the pile of the thorax and abdomen being longer and 

 more abundant; in the hind femora and tibiae being darker, and 

 briefly black ciliate, and in the structure of the abdomen. The ab- 

 domen is not as long, and not as slender basally ; in the male the 

 second segment (first of Schiner) is scarcely more than twice as 

 long as wide ; in the female scarcely twice as long as its distal width ; 

 in both sexes there is an oblique yellow spot on each side distally. 

 In both sexes the remaining segments are less dilated and the black 

 stripes of the mesonotum are narrower. 



34. Bacclia flavipeunis Wiedemauu (l^yrphiis). 



Numerous specimens from Chapada. The identification is not very 

 doubtful if an error is assumed in Wiedemann's description of the 

 abdomen. He speaks of six segments in the male abdomen, whereas 

 there are but five, and the second segment should read " rein braun, 

 an jeder Seite der Spitze mit rotlich gelbem Querflecke, dritte bis 

 fiinfte mit zwei," etc., "der dritte Abschnitt allmiihlig erweitert." 

 The species is allied to the preceding ones, especially the last , the 

 head and legs being as in the last specimen, the markings of the 

 abdomen like those of livida; the hind tibi?e are noticeably black 

 ciliate. The female wings differ markedly in being brown on the 

 basal portion, hyaline distally. The abdomen is much less con- 

 stricted basally than in any of the preceding, the second segment 

 being nearly as broad distally as it is long. Sijrphus rubricosns Wied. 

 seems to be a nearly allied species, but there are also some discrep- 

 ancies here in the markings of the abdomen. Our specimens vary 

 in leuirth from six to nine millimeters. 



