TAXONOMY OF MUSCOIDEAN FLIES — TOWNSFND 25 



and second joints elongate, short, strongly elongate; or only second joint 

 strongly elongate, its length compared with its width or with the third joint. 



1) Lunula (postfront of Berlese) enlarged in middle inferiorly and supe- 

 riorly into a more or less diamond-shaped or rounded plate, like an extension 

 of the facial plate into a secondary one; elongated below between the antennae 

 into a keel-like prolongation, widely separating the antennae, or normal. 



Note. — The lunula readies its greatest development in the Syrphoidea. 



( X. B. — Mesofacial PLATE [= 2 meso facials of Lowne + carina if present, 

 since latter is formed by inner edges of the two mesofacials] + 2 Facialia + 

 antennal ridge + lunula = homologue of Front of larval insects [= ptilinal 

 area]). 



[Behind ptilinal suture] 



2) Eyes absolutely bare ; thinly microscopically hairy, sometimes distinctly 

 so, sometimes indistinctly so ; thickly pubescent, sometimes more so in male, 

 less so in female ; reaching as low as vibrissa?, or lower, or only to middle of 

 face, or very short. [N. B. — In comparisons last mentioned, hold head in full 

 profile with plane of posterior aspect of occiput perpendicular.] 



2) Vertex wide, narrow, comparative width in sexes. 



2) Vertical bristles present or absent, or present only in female; pro- 

 clinate, reclinate, divergent, convergent. 



2) PostvErtical bristles (+ postocellar bristles = lesser oecllar bristles of 

 Hough) large or small, separated or approximated, how many pairs. 



1)2) Front prominent in profile; flattened, or only anteriorly so; bulging, 

 narrow, wide, widened anteriorly, conically produced, of equal width, or 

 not so. 



1) Ocellar plate (stemmata of Rob.-Desv. ; epifrontal of Lowne) triangular, 

 rounded, large, small. 



1) Ocelli separated, approximated. 



1)2) Ocellar bristles (Occllcnborstcn of Brauer and v. Berg.; greater 

 ocellar bristles of Hough) strong, weak, proclinate, reclinate, divergent, 

 vestigial, or absent. 



1)2) Postocellar bristles (a second or posterior pair sometimes present on 

 ocellar plate just behind the two posterior ocelli; + postvertical bristles = 

 lesser ocellar bristles of Hough) present, absent, or represented by fine hairs 

 only. 



2) Preocellar bristles (do. of Hough; small pair on frontalia in front of 

 anterior ocellus) present or absent. 



2) Frontalia (frontalia of Rob.-Desv.; frontals, mesofrontals of Lowne; 

 frontal vitta of descriptions) polished, opaque, wide, narrow, long, short, equi- 

 lateral ; widened or narrowed anteriorly or posteriorly, or in middle ; square in 

 front, notched in front or behind. 



2) Parafrontals (optica frontis of Rob.-Desv.: parafrontals of Lowne; 

 sides of front of descriptions ; geno-vcrtical plates of Hough) swollen, dilated, 

 bare except for frontal and fronto-orbital bristles, hairy, bristly, short, long, 

 wide, narrow, equilateral ; widened before or behind, or both ; prolonged 

 anteriorly. 



1) Frontal bristles (those inserted on the inner edges of the parafrontals, 

 always convergent, often extending posteriorly only to point about half way 

 between ptilinal suture and vertex; transfrontal bristles of Hough) in a single 

 tow, in two or more rows; descending below base of antennae, continuation 



