gg. Bristles almost always present on head, thorax, abdomen and legs.
h. Arista terminal; hind metatarsus enlarged, sometimes ornamented, hind tarsus more or less flattened beneath. Platypezidæ
hh. Flies having a different combination of characters.
i. Head large, eyes occupying nearly the entire head; cell R4+5 narrowed in the margin; small flies. Pipunculidæ
ii. Head and eyes not unusually large.
j. Squamæ (tegulæ, or calyptræ, or alulæ) not large, often quite small, the lower one lacking, or at most barely projecting from below the upper one (antisquama); front of both male and female broad, the eyes therefore widely separated; posthumeral and intraalar macrochæta not simultaneously present; thorax usually without a complete transverse suture; postalar callus usually absent; the connectiva adjoining the ventral sclerites always visible; hypopleural macrochætæ absent; last section of R4+5 and M1+2 with but few exceptions nearly parallel; subcostal vein often wanting or vestigial or closely approximated to R1; the latter often short, basal cells small, the posterior ones often indistinct or wanting; vibrissæ present or absent Acalyptrate Muscoidea
k. Subcosta present, distinctly separated from R1 at the tip; R1 usually ends distad of the middle of the wing; the small basal cells of the wing distinct.
l. A bristle (vibrissa) on each side of the face near the margin of the mouth. Cordyluridæ, Sepsidæ, Phycodromidæ, Heteroneuridæ, Helomyzidæ.
ll. No vibrissæ present.
m. Head nearly spherical, cheeks broad and retreating; proboscis short; the cell R5 closed or narrowed in the margin; legs very long; tarsi shorter than the tibiæ. Calobata and other genera. Micropezidæ