1942] 
Neotropical Syrphidas 
95 
there is an obscure, elongate, yellowish-spot and there is a 
similar, submarginal, basal, posteriorly-pointed spot on the 
third segment. On the fourth segment there is a similar, sub- 
marginal, larger basal spot, each posterior corner of which is 
produced posteriorly; the lateral corner ends bluntly, the 
medial corner is carried back and there is a long, slender, 
curved yellowish-brown line, its outer margin concave. On the 
fifth segment there are traces of four slender, basally ex- 
panded yellowish-brown linear vittae. The pile of the abdomen 
is extremely short and sparse and bristly; on the sides of the 
first segment it is sparse, quite long and fine. Legs: chiefly 
yellow, the middle femora light brown, the hind femora darker 
brown, its apex narrowly yellow, its pile black. Hind tibiae 
black over most of its length; its base and apex are pale, its 
pile, except on the ventral apex black. The hind tarsi are 
whitish -yellow with similar pile. Wings: deeply tinged with 
brown throughout, the anal crease is long but quite obsolescent. 
The apex of the subapical cross vein is recurrent. 
Holotype: a male. Villarica, Paraguay, III (F. Schade col- 
lector). 
Baccha olga n. sp. 
Characterized by the sepia-brown stigmal cell, apical spot 
and small central spot of the wing, the black face and spatulate 
abdomen. Related to lanei Curran and bigoti Austen. 
Female. Length 10 mm. Head: the face, front and cheeks 
are shining black with a slight bluish tinge; the sides of the 
front are narrowly covered with pale grey pubescence to above 
the middle where it extends transversely across in an inter- 
rupted band. It is also continued down the eye margins where 
it spreads out on either side of the face on the lower half, leav- 
ing a narrow middle lower stripe bare. Profile of face straight 
and retreating, its pile and the very few hairs of the front 
white. Antennae brown, the third joint blackish-brown, its base 
and ventral margin narrowly pale yellow. Arista light brown. 
Thorax: mesonotum and scutellum black with a metallic 
brownish or golden caste, its pile white, and appressed except 
on the anterior border and except for a few erect hairs in front 
of the scutellum. Scutellar pile wholly erect; pleurae white 
pilose and pubescent over the mesopleurae, sterno and noto- 
pleurae, the pile of the latter spreading over the anterior edge 
