27 (32). Third antennal joint ringed; A, IV, 6, if present (plate III, 1-9) apical.
28 (29). Costa ending at apex of wing (plate V, 1).
Stratiomyidæ, XV
29 (28). Costa around the hind margin (plate V, 2).
30 (31). Squamæ very large.
Tabanidæ, XVI
31 (30). Squamæ very small.
Part of Leptidæ, XVII (genus Xylophagus)
32 (27). Third joint of antennæ (plate III, 10-55) not ringed.
33 (55). Arista terminal or wanting (plate III, 10-26, 28-32, 35-40, 48)