May, 1911.] 
Two Species of Syrphidae. 
34i 
femora, distal portion of tibiae, and the tarsi brown. Abdomen 
black, with four yellow cross bands, the first consisting of two 
large ovate spots, narrowly separated and reaching the lateral 
margins in nearly their full width; second and third cross-bands 
broad separated from the lateral margins by a black narrow 
keeled border; they are much narrower in the middle of the seg- 
ments, the front margin straight, touching the anterior edge of 
the segments ; fourth band similar, but much smaller and attaining 
the margin; all the black is velvety opaque except the narrow 
posterior margin of the segments which is shining, dilated in the 
middle. 
Syrphus torvus Osten Sacken 
LARVA. 
Length, 10-12 mm., width 3-4 mm., height about 2 mm. 
Shape sub-cylindrical, tapering rapidly in front to the mouth 
parts, slightly narrowed but blunt and emarginate at posterior end. 
The body consists of twelve more or less apparent segments 
each except the first two and the last crossed by a transverse row 
of twelve light-colored spines. Ten of these are in line, the most 
ventral on each side being situated in front of the others. The 
integument is raised into numerous transverse folds continued 
laterally into a distinct longitudinal keel on each side (Fig. 10). 
First three body segments small, retractile, gradually thicker; 
next eight sub-equal; terminal segment flattened, bearing on its 
dorsal surface the caudal spiracles. These as in Didea are 
borne upon two short cylindrical approximate appendages and 
are placed within clefts at the summit of three radially arranged 
carinae on each appendage (Fig. 13). These carinae are narrower 
and longer than those in Didea. The rounded plate-like piece is 
present on the anterior part but the surface shows only a few 
blunt projections. On the ventral part of this segment is the 
opening of the alimentary canal. The mouth-parts are terminal 
and are similar to those of Didea except for an additional pair of 
black chitinous recurved hooklets at the sides (Fig. 11). Sur- 
rounding them on the first two segments are a number of small 
sense papillae (Fig. 11, h). The first segment also bears the anten- 
nae (Fig. 11,/). These are very small, similar to preceding species. 
Between the second and third segments dorsally is a pair of small 
brownish anterior spiracles (Figs. 10a, 1 lg) ; conical, the semi- 
circular slit guarded by seven rounded teeth (Fig. 12). 
The general color of the larvae is brown pink. The integ- 
ument is tough but transparent; naked but very finely papillose. 
The black mid-dorsal blood vessel is more prominent than in 
Didea and in the living active larvae the blood may be seen 
pulsating regularly from posterior to anterior end. Laterad to 
this blood vessel are two long yellowish bundles of fat irregularly 
