Vol. iN No. 4.] Notes on the Freshwater Fauna of India. 115 
N.S.] 
skin; but I have not been able to watch the process. 
On most tubes I have examined there have been colonies. of 
the Protozoon Epistylis flavicans, which is common in the tanks on 
the roots of duckweed during the winter months. A close exa- 
mination shows that these colonies are not normal ones like those 
enables it to obtain at once food and shelter from animals lower in 
the scale of structure than itself. Possibly the case is in some 
respects paralleled by that of the Amphipod Phronima, which is 
“found in the empty tests of Ascidians ; but it is at once less com- 
plex and more unusual than that of the other su 
as Dorippe facchino) which carry about with them living Coelenter- 
ates as a protection and not as ; 
As regards other enemies of Hydra orientalis I have little 
information. I have repeatedly noticed that individuals confined 
attack is made ; for the larva feeds chiefly, if not entirely, by night. 
It is evident, therefore, that the nematocysts of Hydra do not 
protect their possessor entirely from the attacks of Insects, any more 
than those of marine Coelenterates do from the attacks of fish.' 
PREY. 
The food of Hydra orientalis is by no means homogeneous. 
Cladocera and Copepods are commonly eaten, more especiall the 
4 Octrarndia and . 1 
former; but ’ y even members of these other 
groups, are merely held for a few seconds on the tentacles and 
then dro ‘ tifers and minute Oligochete worms 
great part, and undoubtedly a very large part of the food consists 
of newly-hatched Insect larve, chiefly Dipterous and Neuropter- 
ous. Young individuals, as I have noted, of the very Chironomid 
| See Ashworth and Annandale in Proc. Roy. Soc. Edin. XXV, 1904, p. 3 
(note). 
