434_ NEW YORK STATE MUSEUM 



€ies yellowish in color, often colorless; the larger ones often a 

 deep red. All Chironomns larvae build a cylindrical, gelatinous, 

 or silky case, in which they usually are hidden. The larvae of 

 Tanypus possess a distinctly, segmented, somewhat flattened 

 body, with long conical anal prolegs, an elongate triangular 

 head, with distinct eye spots. They do not appear to build a 

 larval case." Those Ceratopogon which in the adult state do not 

 possess hairy wings, have aquatic larvae. These are very elon- 

 gate, snakelike in form, with a conical head, no thoracic or 

 caudal appendages, save sometimes a few bristles at the tip of 

 the last segment. 



The pupa of Chirononius usually lies hidden in the larval case, 

 keeping the water surrounding it in circulation by the undulat- 

 ing motion of the abdomen. The pupa of Tanypus is active and 

 resembles that of Culex. The pupa of Ceratopogon is more elon- 

 gate than that of Tanypus, and is not active, but floats nearly 

 motionless, with its body in a vertical position. 



For determining the getiera of the imagos, the table given 

 by Williston in his Manual of the Xorth American Diptera is most 



useful. 



Chirononius (sens, str.) sp. 

 Plate 49 

 A large number of larvae and pupae were taken from the 

 stomachs of brook trout, as has been described by Professor 

 Xeedham in this bulletin. Many specimens were examined and 

 all found to belong to the same species. The species evidently 

 being of gi'eat importance as fish' food, it is desirable that it may 

 in the future be recognized, and therefore I herewith describe 

 it. Many characters here given apply to the genus as well. 



Body slender, 12 segmented, full grown specimens about 18mm 

 in length. Occasionally, still living specimens were found 

 within the fish stomachs; these possessed the brilliant red color 

 so characteristic of certain Chironomid larvae. At the anterior 

 end of the first segment and at the posterior end of the 13th 

 are pairs of prolegs. The head is small, dark brown, heavily 

 chitinized. a little longer than wide. The sclerites of the head 

 consist of a dorsal, ventral and iwo lateral plates, besides a 

 number of smaller ones. The dorsal sclerite resembles that 

 shown on plate 50, figure 4; but there are three pairs of bristles 



