88 NEW YORK STATE MUSEUM 



hh Full-grown larva over 6 mm. in length ; mandible not 



transversely wrinkled 

 i Labium with its teeth rounded, pl.20, fig.9 



35. Diamesa waltlii. 1 

 ii Labium with its middle tooth broadly truncate 



37. Thalassomyia fusca 

 NOTE. See addenda for several anomalous species. 



Pupae 

 a Pupa floats nearly motionless in a vertical position at the surf ace of the 



water, pl.17, fig.ll (Group Ceratopogon) 



a a Pupa not as above 



6 Active pupa swimming with a jerking motion in the water like a culex 



pupa, pi. 19, fig.8 (Group T any pus) 



1)1) Not culexlike 



c With long setae or filaments at caudal end 



d Caudal filaments very numerous and forming a caudal paddle, 



pl.22, fig.14, and pl.26, fig.15 

 e Thoracic respiratory organs a tuft of filaments, pi. 16, fig.2 



38. Chironomus 



ee Respiratory organs consisting of a main shaft with lateral hairs 

 or setae. Abdomen with setae and bristles. 



42. Tanytarsus 

 dd Caudal appendage with long setae 



e With eight long setae on each side of caudal appendage, pi. 36, 



figs. 4 and 5 25. Corynoneura leinnae 



ee With a tuft of long setae on each side; thoracic respiratory 

 organ a simple finger-like process, pi. 34, figs. 5 and 8 



31. Hydrobaenus 

 cc With three or four pairs of short setae, a plate-like sucker or with a 



paddle 

 d Plate-like sucker at caudal end, pl.34, figs. 14 and 15 



29. T e 1 in a t o g e t o n ( St Paulii) 

 dd With two or three pairs of short setae or with paddle 



e Without thoracic respiratory tubes. Abdominal segments with 

 a fringe of conspicuous spines or setae or projections, pi. 48, 

 fig.13, and pl.50, fig.10 in Bui. 68 N. Y. State Museum, 1903 



f 35. Diamesa 

 37. Thalassomyia 

 44. Metriocnemus 



With respiratory tubes. Abdominal segments usually without a 

 fringe of prominent setae, pl.24, fig.24, also pl.24, figs. 13, 14, 15 



39. Cricotopus 

 41. Orthocladius 



'The larva of Thalassomyia congregata (an European species) 

 has a labium like Diamesa waltlii. 



