May, 1911.] Two Species of Syrpliidae. 341 



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 b\^ 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; tenninal 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 tenninal 

 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, 11^); 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 



