434 NEW YORK STATE MUSEUM 
cies yellowish in color, often colorless; the larger ones often a 
deep red. AJl Chironomus 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 Chironomus 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 genera of the imagos, the table given 
by Williston in his Manual of the North American Diptera is most 
useful. ; 
Chironomus (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 
Needham in this bulletin. Many specimens were examined and 
all found to belong to the same species. The species evidently 
being of great 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 12th 
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 two 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 
