308 



SYHPHID^. 



Head about as broad as thorax, someuliat flaitened ; eyes bare, 

 wide ajnirt in d' , still more so in 5 ; frons iu J geneially sligbtly 

 narroxAed about the middle; face lounded, very ])ubescent, iiioutb- 

 border not prominent ; antennae porrect, appir-ximate at base, 1st 

 joint the longest, cylindrical, 2nd about one-fourfh as long as the 

 1st, broader at tip and longer on lower side, 3rd joint of irregular 

 shape, longer tlian 2nd, but usually only as long as, or shorter 

 than, 1st, upper side nearly flat, lower side gently rounded ; arista 

 sub-basal, bare, somewhat thickened. :Z7ior«.rsubqiiadi'ate, arched, 

 with rather dense pubescence ; scLitellum rather large, in many 

 species with two blunt tubercles or sjdnes near tlie tip. Abdomen 

 about as long as thorax, rounded, well arched and curved down- 

 ward ; 4th segment in <S nearly bait' the length of the abdomen, 

 in 2 'Itli and 5th segments subequal, 5ih segment in S often 

 very small, twisted sideways to the left so that the bulbous base 



Fig. G5. — Microdon hellus, sp. nov., 5- 



of the large genitalia is pronn'nent, witli ap])endages concealed 

 beneath the body. Legs sliort and thick, tarsi wide. Wings com- 

 paratively short, venation recalling that of Evments, marginal cell 

 widely open ; 3rd vein sinuous, with a stump of a vein projecting 

 backwards nearly half-way across 1st posterior cell; latter closed 

 a long distance from border of wing by the strongly recurrent tip 

 of the 4th vein ; anterior cross-vein distinctly 1 elbre middle of 

 discal cell ; apical portion of 5th vein rectangular, nearly upright ; 

 anal vein slightly but distinctly curved at tip ; squamae large. 



liange. Europe, North and South Africa, Orient, Tasmania, 

 North and South America. 



Life-history. That of M. mutahilis, L,, and of certain other 

 European species is known. The larvae are so unlike those of 

 any other insects that when first discovered they were acttially 

 described as mollu.-cs by two authors, writing independently, 

 in two consecutive years, and several years elapsed before 

 Schlotthauber cleared up the mystery, the matter being more 



