48 DITEHAM DIPTERA. 



VI. 



6(21). X.5. absent (IV. 10). 



7 (8). Fourth tarsal joint heart-shaped and short. 



71. Thalassomyia, Schin. (402. frauenfeldi, Schin.) 



8 (7). Fourth tarsal joint normal. 



9 (16). Wings bare. 



10 (11). Fore metatarsus distinctly longer than the fore tibia. 



Chironomus, Mg. (72) 



11 (10). Fore metatarsus about equal to or shorterthan thetibia. 



12 (13). Legs with white rings. Cricotopus, v.d. Wulp (73) 



13 (12). Legs not white ringed. 



14 (15). V.5.b. normal, bent gradually down to the hind 



margin. Orthocladius, v.d. Wulp (74) 



15 (14). V.5.b. bent down and turned up at the hind margin. 



Camptocladius, v.d. Wulp (75) 



16 (9). Wings hairy. 



17 (18). Fore metatarsus longer than the tibia. 



Tanytarsus, v.d. Wulp (76) 



18 (17). Fore metatarsus shorter than the tibia. 



19 (20). Tarsi stout, hind tibiae thick, broad, and hairy. 



77. Eurycnemus, v.d. Wulp. (496. elegans, Mg.) 



20 (19). Tarsi slender, hind tibiae not specially broad. 



Metriocnemus, v.d. Wulp. (78) 



21 (6). X.5. present (IV. n). 



22(23). Female antennae 7-8-jointed, male 15-jointed, eyes 

 round. Diamesa, Mg. (79) 



23 (22). Antennae 15-jointed in both sexes, eyes not round, 



indented on inner sides. Tanypus, Mg. (80) 



24 (5). Dorsum, viewed sideways, only moderately arched, 



and not overhanging in front; legs moderately 



long, and often very strong; V.3. often with a 



X-vein to V.I.; V.2. absent; the long hairs of the 



male antennae brush-shaped (II. n). 



Ceratopogon, Mg. (82) 



tables op species. 

 72. Chironomus, Mg. 



1 (16) (27). Wings with a small spot or tick on X.4., but no 

 other spot or streak, 



