LX 145. NYCTERIBIDÆ: wingless parasites on bats; with small heads held in a curious posture. ANALYTICAL TABLE OF FAMILIES ORDER—DIPTERA 1 (141). Insects with the head distinct from the thorax, with one pair of wings, one pair of halteres, 5-jointed tarsi, proboscis not spirally coiled; with a well defined pupal stage intermediate between the larval stage and the perfect insect. 1-1/2 (52-1/2). Frontal lunule absent. SUB-ORDER I. ORTHORRHAPHA (comprising 25 families); flies with "mummy-pupæ," _see plate_ VI, figs. 38 and 39. 2 (25). Antennæ many-jointed (_plate_ II). NEMATOCERA (thread-horns)— 3 (4). Vein endings round the margin (_plate_ IV, figs. 1, 2, 3) not more than 6. CECIDOMYIDÆ, II 4 (3). Vein endings more than 6. 5 (20). Thorax (_plate_ VI, 31) without B, I, 8 conspicuous. 6 (15). Costa ending at apex of wing (_plate_ IV, 4-11). 7 (12). Ocelli as in _plate_ I, or as in _plates_ VI, I and II, 4. 8 (9). Discal cell (O, 4_b_ or O, 5^2) present (_plate_ IV, 16). RHYPHIDÆ, XIV 9 (8). Discal cell absent (_plate_ IV, 4-7). 10 (11). Antennæ long (_plate_ II, 3-6); or, if short, coxæ elongated. MYCETOPHILIDÆ, III 11 (10). Antennæ as in _plate_ II, 7 and 8; coxæ not elongated. BIBIONIDÆ, IV 12 (7). Ocelli absent. 13 (14). Antennæ (_plate_ II, 9) shorter than B; wings (_plate_ IV, 9) broad. SIMULIDÆ, V 14 (13). Antennæ (_plate_ II, 10, 11) longer; wings narrow (_plate_ IV 9-11). CHIRONOMIDÆ, VI 15 (6). Costa (_plate_ IV, 12-14) around hind margin. 16 (17). Wings held roof-like, hairy; X only at base (_plate_ IV, 12). PSYCHODIDÆ, VIII 17 (16). Wings flat over D; X on middle of wing. 18 (19). Veins hairy (_plate_ IV, 13). CULICIDÆ, IX 19 (18). Veins bare. 19_a_ (19_b_). Antennæ long; V, 4 and V, 2 forked; X, 4 (_plate_ IV, 14) ending in V, 2. DIXIDÆ, X 19_b_ (19_a_). Antennæ very short but 11-jointed; no veins forked. ORPHNEPHILIDÆ, VII 20 (5). Thorax (_plate_ VI, 32) with a strong cross seam. 21 (22). V, 6 absent (_plate_ IV, 15). PTYCHOPTERIDÆ, XI 22 (21). V, 6 present. 23 (24). V, 1_a_ ending in costa and (_plate_ IV, 17-22) united to V, 1_b_ by X, 1_b_; last joint of palpi (_plate_ VI, 4) never whip-like. LIMNOBIDÆ, XII 24 (23). V, 1_a_ ending in V, 1_b_; and, except for X, 1_a_ at its base, not united by X (_plate_ IV, 23-26); palpi (_plate_ VI, 5). TIPULIDÆ, XIII 25 (2). Antennæ short, 3-jointed (_plate_ III); 3rd joint sometimes ringed. BRACHYCERA (short-horns)— 26 (140). Wing veining normal; X-veins present.