6. STRATIOMYS 147 



Head semicircular when seen from above, wider than high; face slightly or 

 distinctly arched, retreating, not much produced just below the antennae ; jowls 

 fairly broad ; back of the head in the male slightly inflated on the lower part, but 

 almost flush with the eyes on the upper part ; in the female considerably more 

 inflated, and forming a rim or broad collar against 

 the eyes which is often conspicuously yellow ; frons 

 moderately produced. Proboscis not prominent, com- 

 paratively small, but with large sucker-flaps ; palpi 

 small, jointed, with the end joint thickened ; mouth- 

 opening small, ovate but produced in front. Eyes bare 

 or hairy, and sometimes differing in this respect in the 

 sexes ; always widely separated in the female, but 

 always closely approximated on the frons in the male, 

 though with a line of dividing pubescence, and usually 

 with the lower facets smaller than the upper ones 

 and sometimes sharply and conspicuously contrasted. 

 Antennae conspicuously elongate, twice as long as the 

 head, and placed at about the middle of the head in 

 profile : basal joint cylindrical, four or more times as 



long as the short second, and the basal joint of both ^'«- ^^^-SMnys furcata ?. 

 antennae very contiguous from the base to the tip, but 



the other joints widely diverging (fig. 132) ; the third joint very long and thin, and 

 with five or six annulations,* much longer than the basal joint, and without any 

 terminal style or bristle unless the last annulation represents one ; the two basal 

 joints of the antennae bear some tiny adpressed bristles, but the annulated third 

 joint is bare. 



Thorax rather longer than broad, and with moderately or conspicuously dense 

 equal pubescence in which there is no trace of any bristles or long bristly hairs, 

 suture distinct. Scutellum semicircular, with one pair of marginal spines set well 

 apart. 



Abdomen distinctly broader than the thorax, almost quadrate and with the 

 fore angles so little rounded as to leave pronounced shoulders, slightly arched over 

 the middle of the disc but leaving broad flattened margins within which the wings 

 lie when at rest ; sides parallel from the middle of the second segment to near the 

 end of the fourth segment, and bearing a more or less dense suberect pubescence 

 on the arched part, while that on the flattened sides is more sparse and depressed. 

 Genitalia of the male small, but obvious. 



Legs rather thick, simple in structure, and bearing only moderate inconspicuous 

 pubescence. 



Wings (tig. 125) with the venation of the Stratiomyinw, in which the anterior 

 veins are strong and crowded together, the radial vein being extremely close to the 

 subcostal, but the exterior and posterior veins are faint. Cubital vein obviously 

 forked ; veinlets from the discal cell strongly bent and not quite extended to the 

 wingmargin ; anal cell closed well before the wingmargin ; discal vein very thin 

 though not faint until near the discal cell, when it becomes blackish and continues 

 so until the fork which forms the two diverging basal sides of the pentagonal discal 

 cell, and this blackish portion is densely though minutely downy before the fork 

 and still downy though in a still more minute form on the branches of the fork ; 

 wing-membrane bare. Squamae (alar) comparatively small but with a thick margin 

 and a short slight fringe ; thoracal pair large and rather upraised, with no obvious 

 margin but bearing dense woolly pubescence all over. 



Metamorphoses well known ; the rat-tailed larvae live in water, mud, and moist sand. 

 Walker has given a rather full account of the larva of *S'. chamceleon {S. iwtamida ?) 

 in Insecta Britannica Diptera, vol. i., p. 14. Dr D. Sharp confirms the opinion that 

 their larvae live on minute life, and considers that they congregate in the neighborhood 

 of drowned creatures in search of the minute organisms which abound there. 



This genus is well circumscribed and easily distinguished in this sub- 

 family by the basal joint of the antennae being four or more times as long 



* Luudbeck calls special attention to the annulations of the flagellum, and I find (as he states) that 

 .S. potamida and S. cliamceUon have the ordinary fourth annulation subdivided so that a short fifth annulation 

 precedes the last one ; I cannot trace this annulation at all in ,s'. longicornis, but it occasionally occurs in 

 a. furcata as in fig. 132, 



