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) 34 (46). V, 3 forked (_plate_ V, 3-10, 13). 35 (45). O, 6^1 long, extending (or nearly) to hind margin, or entirely wanting (_plate_ V, 3-9, 13). 36 (39). C, I, (II) much enlarged, appearance of 3 foot-pads (_plate_ VI, 9) 37 (38). Squamæ small, not covering C, III; O, 6^1 long and distinct (_plate_ V, 3); long bodied flies, head of normal proportions. _Part of_ LEPTIDÆ, XVII 38 (37). Squamæ very large, hiding the halteres; O, 6^1 absent (_plate_ V, 13); short round-bodied flies with very small heads. CYRTIDÆ, XXII 39 (36). Empodium small, only 2 foot-pads apparent (_plate_ VI, 10, 11). 40 (41). Vertex hollowed out between the eyes (_plate_ VI, 28). ASILIDÆ, XVIII 41 (40). Vertex flat or raised, eyes not protruding. 42 (43) (44). V, 4 ending in 3 branches (_plate_ V, 6, 7) between V, 3 and V, 5. BOMBYLIDÆ, XIX 43 (42) (44). V, 4 ending in 4 branches (_plate_ V, 8) between V, 3 and V, 5. THEREVIDÆ, XX 44 (42) (43). V, 4 ending in 2 branches (_plate_ V, 9); antennæ (_plate_ III, 23) without A, IV, 6. SCENOPINIDÆ, XXI 45 (35). O, 6^1 short (_plate_ V, 10) not nearly reaching hind margin. _Part of_ EMPIDÆ, XXIII 46 (34). V, 3 not forked (_plate_ V, 11-12, 14-17). 47 (52). Alulæ absent or rudimentary. 48 (51). Apex of the wing rounded. 49 (50). X, 4 placed generally beyond X, 5^1, at most only a little before it; V, 5 with 2 X-veins bounding a discal cell (_plate_ V, 11); or, if only one, then X, 5 is placed before, or, at most (_plate_ V, 12) only a little beyond X, 4. _Part of_ EMPIDÆ, XXIII 50 (49). X, 4 placed very near the base of the wing; V, 5 with only one X-vein placed far beyond X, 4; no discal cell (_plate_ V, 14, 15). _Part of_ DOLICHOPODIDÆ, XXIV 51 (48). Apex of the wing (_plate_ V, 16) pointed. LONCHOPTERIDÆ, XXV 52 (47). Alulæ present. 52-1/2 (1-1/2). Frontal lunule (_plate_ VII, 5) present. SUB-ORDER II. CYCLORRHAPHA (families XXVI—LX); flies which escape from a puparium, formed of the indurated larval skin, through a circular orifice made by pushing off its head end (_plate_ VI, 37). PROBOSCIDEA— 53 (54). Antennæ (_plate_ III, 39, 40) with a long seta or bristle.