1942 ] 
Neotropical Syrphidce 
91 
Microdon banksi n. sp. 
Because of the shape of the arista this species slightly resem- 
bles pachystylum Will., but it is quite different in coloration 
and venation and other details. 
Female. Length excluding antennae 6.5 mm.; antennae about 
2 mm.; wing 5 mm. Head: eyes very widely separated, the 
upper occiput extremely thickened but with rounded posterior 
margin, the vertex shining brownish-black; the pile just in 
front of the ocelli, just behind it and again just in front of the 
antennae black, elsewhere the pile of the head is wholly shining 
pale brassy. Along the upper occiput near the eyes the pile 
appears to be directed towards the eye margins ; upon the inner 
upper eye margins it is directed towards the ocelli; from a 
point in the middle of the very broad front it appears to be 
directed in all directions, and opposite this mid-point it is upon 
the eye margins directed first towards the antennae and then 
down ventrally towards the face. About the antennae the pile 
is slightly more reddish and upon the face more whitish. Face 
short, not in the least produced, quite convex, most so upon 
the lower half, the pile thick, abundant, shining and directed 
downward but not flattened. Viewed from in front the sides of 
the face are more equally wide, perhaps barely wider below 
than across the antennae. The ground color of the face in front 
is shining brownish-black. Antennae elongate, the first joint 
but little over one-half as long as the third and together with 
the second and the extreme base of the third reddish-brown. 
The third joint is black, slightly narrower in the middle, upon 
its outer surface slightly curved, about twice as thick as the 
also outwardly curved first joint; arista basally produced from 
the outer side, very short, and thickened into a basally blunt 
spear-shaped structure, the tip needle-shaped, the whole arista 
light reddish. Thorax: almost as wide as the head, moderately 
shining brownish-black with more or less erect black pile except 
as follows: some pale brassy pile bordering a lunate, shallow 
depression on each half of the anterior part of the thorax, again 
narrowly across the mesonotal transverse suture, upon a sub- 
lateral stripe along the posterior half of the thorax and again 
in acute short triangles, one on each side, reaching forward 
from the posterior margin of the mesonotum. Pile of scutellum 
wholly erect and pale; its ground color dark blackish-brown, 
