IQO H. C. EFFLATOUN. 



DIAGNOSIS: — An exceedingly common, rathor small, 

 narrow, almost bare fly, which can be at once recognisod by the 

 absence of the vena spuria, the very thick hind femora, which are 

 serrate beneath and possessing individual strong spines and a Uirge, 

 stout basai spine ; antennse (hirk bi-own. 



DESCRIPTION:— Mule: Face as well as tlic l'rons cntirely 

 covered with pure silvery white or pale yellowish-whitc dust, and 

 with a few white hairs on the lower part of the face at the sides; 

 face descending below the atcnnse in a gentle curve to the iipper 

 month-edge, which is its most prominent part ; lielow this the face 

 retreats to the lower mouth-edge, and thence iii a straight line to 

 the jowls ; the lower end of the vcrtex is thin and rather flat, 

 and about its middle it is a little wider owing to the incurved 

 margin of the eyes (but not so mueh as in Sphrrroi>hoi'iii)\ tho 

 jowls and ail the vertex are covered with pure silvei'y- white dust 

 and jwssess a few white hairs, but the upperniost part of the ocei- 

 put (innnediately liehind the vertex) possesses a few yellowisli 

 hairs, and the dust is usually greyish. Vertex long, possessing 

 silvery-white dust and a few hairs on the front liai f of the vertical 

 triangle, liut witli its hind or upper part black and bearing incons- 

 picuous yellowisli pubescencc. Frons quite sniall, little produced, 

 and quite free from pubescence. Eyes meet for a distance which 

 is somewhat longer than the length of the frons, with the facets 

 on the upper front part rather dilated. Antennse with the two 

 basai joints blackish or reddish-brown but with the third joint 

 either entirely blackish or in great part black with the tip very 

 dark reddish-brown ; arista very dark reddish-brown, gradually 

 tapering towards the tip. Ail the three joints, especially the third 

 possess exceedingly fine whitish dust. 



Thorax rather duU black, thînly punctate and with the 

 postalar calli reddish-brown or dark brown, and with traces of 

 two lighter lines on the front part of the dise; the humeri and 

 the sides down to tlie suture, as well as the pleurse are covered 

 with dust which varies from pure silvery-white to whitish-grey ; in 

 the elongate hollow immediately above the postalar calli it is also 

 greyish. The pubescence is extremely fine, short and inconspicuous, 

 but fairly dense, even and uniformly pale. Scutellum very flat on 

 the dise and possessing short pale hairs with a few tiny incons- 

 picuous bristles at the tip. 



Abdomen with the basai segment dull l)lack but greyisli 

 on the two basai corners. The second segment is yellow, 

 with a broad triangular blackish band always présent on 

 the lower margin ; the upper margin is usually yellow like the 

 rest of tlie abdomen, Init sometimcs, it bears a small triangular 



