FAUNA OP A SMALL BROOK 
371 
fonuB are predaceous upon the smaller animals, such as Entomo- 
stracha, and have been known to feed upon May fly nymphs. 
Their transparency enables them to feed to great advantage 
without being exposed to the attacks of other forms. Their 
other habits are similar to those of Culex and they also are mem- 
bers of the free-swimming association. 
A specimen of Corethrella sp ? in the larval stage was taken 
from one of the pools. The habits of this genus as far as known 
are very similar to those of the two preceding genera. 
2. Chironomidae — ^Midges. Larvae of the genus Chironomus 
were taken by dredging the pools on the various dates men- 
tioned above. They were taken also on April 24 in their arti- 
ficial burrows on the rock shelves which had been a part of the 
rapids during greater flow of water. These feed upon decaying 
vegetable matter and are confined to the bottom association al- 
though they occasionally swim about free from the bottom. 
A few specimens of the genus Ceratopogon were taken in the 
larval stage April 17. These are free-swimming forms wriggling 
about for the most part among the aquatic plants near the sur- 
face. It is presumed that this genus is carnivorous in Its food 
habits. 
3. Tipulidae — Craneflies . Tipulid larvae were taken in num- 
bers from the shallow, muddy bottomed upper part of the stream 
on April 24. They also occur abundantly near the edge of the 
pools partly buried in the mud. Their distribution in the pools 
is limited to those depths that will enable them to reach the sur- 
face to obtain air with the specially adapted posterior end. In 
some cases the little depressions, caused by surface tension, 
which mark the location of the breathing apparatus of the Tipu- 
lid larvae fairly dot the marginal waters of the pools. They 
feed on the decaying plant matter in the muddy bottom, and be- 
long to the bottom association. A single adult was taken April 
24 from the grass beside the brook, but the species has not been 
determined. 
A single pupa, similar in most characters to the pupae of cer- 
tain Tipulidae was taken from the rock shelf of the rapids April 
24. 
4. Stratiomyiidae — ^Soldier flies. Larvae of Btratiomys were 
taken from all of those places recorded for Tipulid larvae but in 
decidedly fewer numbers. These larvae crawl about over the 
bottom in shallow places with the posterior segments turned up- 
