258 



and legs closely fused to thorax; wings extending to apex of third 

 segment or slightly beyond it; legs extending to apex of seventh seg- 

 ment, their apices forming a slightly concave transverse line. Ab- 

 domen with numerous microscopic dorsal setulae; spiracles of first 

 segment obsolete, those on segments 2-7 elevated ; metanotum cen- 

 trally concave anteriorly, so that its length at center is about half that 

 of first abdominal segment, while laterally it is as long as the latter ; 

 second segment longer than any of the others ; seventh about half as 

 long as sixth; eighth and ninth segments combined equal in length 

 to sixth. 



The foregoing descriptions were made from a larval exuvium and 

 pupae, the species being obtained by me in the Augerville woods near 

 Urbana, 111., June 23, 1916. The larvae were feeding on a fungus 

 growing upon the under side of a log lying upon the ground. 



The principal differences between this species and Polylcpta lep- 

 togaster, exclusive of any that may exist in the respiratory system, lie 

 in the structure of the mandibles and of the maxillae, and in the ab- 

 sence of locomotor spinules. Schmitz figures the cephalic dorsum as 

 entire in Polylepta, which may be an error. 



Family SCI ARID AB 



The members of this family have until recently been classed as a 

 subfamily of Mycetophilidae, but in this paper and in some papers by 

 other authors they are accorded family rank. There is a striking 

 uniformity of structure in the imagines of Sciara — the genus that con- 

 tains by far the largest number of the included species — and in the 

 larvae known to me there is also a striking similaritv in appearance 

 and structure. I have reared but few species, and my generalizations 

 are based upon these. 



FAMILY CHARACTERS 



Larva. — Head like that of Mycetophilinae. differing principally in 

 having 2 narrow bands of chitin connecting the lateral sclerites on 

 their ventral surface (PI. XXXVIII, Fig. 2), in having the median 

 .dorsal sclerite distinctly and often rather abruptly constricted at or 

 slightly beyond middle (PI. XXXVIII, Figs. 6, 9), and in the absence 

 of the clear spot below antennae. The mandibles are almost quad- 

 rate in outline, have 3 large apical teeth, and usually 2 or 3 smaller 

 ones at inner angle of apex (PI. XXXVIII, Fig. 14). The general 

 shape of the head in species known to me is subquadrate (PI. 



