PLATYPEZIDÆ, XXVI 54 (53). Antennæ (_plate_ III, 48) with a short seta or spine. _Part of_ CONOPIDÆ, XXIX 55 (33). Arista dorsal (_plate_ III, 27, 33, 34, 41-47, 49-55). 56 (61). O, 6^1 long (_plate_ V, 18-21-1/2) extending nearly to hind margin: D without strong bristles (macrochætæ). 57 (60). Proboscis of moderate length (_plate_ VI, 12-16) generally retracted. 58 (59). Vena spuria (_plate_ V, 18) absent; A, II very large; O, 4^2 open. PIPUNCULIDÆ, XXVII 59 (58). Vena spuria present (_plate_ V, 19-21); O, 4^2. closed; A, II moderate. SYRPHIDÆ, XXVIII 60 (57). Proboscis projecting far in front, very thin and long, often double-kneed (_plate_ VI, 27); no vena spuria (_plate_ V, 21-1/2). _Part of_ CONOPIDÆ, XXIX 61 (56). O, 6^1 short, not nearly reaching margin, or absent (_plate_ V, 12, 22-39) abdomen often with strong bristles. 62 (63). Proboscis and palpi atrophied. ŒSTRIDÆ, XXX 63 (62). A, VIII, 3 and 4 distinctly present. 64 (67). X, 5^1 absent, X 5^2 present, _i.e._, only one X-vein on V, 5 and that beyond X, 4. 65 (66). X, 4 very near base of wing (_plate_ V, 14, 15); X, 5 far beyond X, 4. _Part of_ DOLICHOPODIDÆ, XXIV 66 (65). X, 4 more towards middle of wing (_plate_ V, 12, 36, 37) nearer X, 5. 66_a_ (66_b_). Proboscis directed straight downwards. _Part of_ EMPIDÆ, XXIII (genus Stilpon) 66_b_ (66_a_). A, VIII, 3 retracted [ordinary Muscid type] pass on to 108 of this table. 67 (64). X, 5^1 present, that is, a X-vein on V, 5 before, or under X, 4; or no X-veins on V, 5. 68 (69). No X-veins on V, 5. _Part of_ PHYTOMYZIDÆ, LIV 69 (68). At least X, 5^1 present, generally also X, 5^2. 70 (75). Squamæ distinctly present though sometimes small. MUSCIDÆ CALYPTERÆ— 71 (74). V, 4 angled or bent towards V, 3 (_plate_ V, 24-29). 72 (73). D with E (macrochætæ and hairs) on middle segments; otherwise A, IV, 6 is bare or bare on the tip-half (_plate_ III, 49-50). TACHINIDÆ, XXXI 73 (72). D without macrochætæ though often with rather strong hairs; A, IV, 6 fully plumed or combed (_plate_ III, 51). MUSCIDÆ, XXXII 74 (71). V, 4 going straight or nearly straight to margin (_plate_ V, 30). ANTHOMYIDÆ, XXXIII 75 (70). Squamæ absent or rudimentary. MUSCIDÆ ACALYPTERÆ— 76 (105). V, 1_a_ distinctly present, nearly as thick as V, 1_b_, which generally ends in the fore margin at or beyond the middle of the wing (_plate_ V, 31, 32, 34). 77 (84). Vibrissæ present (_plate_ VIII, 2) together with more or less hair. 78 (79). V, 4^4 four or five times as long as V, 4^3 (_i.e._, X, 5^2 nearer X^4 than to wing margin). HETERONEURIDÆ, XXXVII 79 (78). V, 4^4 about equal to V, 4^3, or only a little longer.