Vol. II, No. 4.] Notes on the Freshwater Fauna of India. 111 
LN.S.] 
ee very commonly upon the living shell, although I have not 
een them on that of any other genus s and very rare rely on any 
otter support. Two other Indian Polyzoa,' Hislopia thousboi and 
Pectinatella Penagh as been taken on Paludina shells. The Pro- 
tozoon fauna of Paludina shells seems also to be large. 
n several occasions, in January and February, I too 
ooroiiial of Epistylis plicatilis (which i found on Limneeus in 
in the same situation and on operculum ; while the 
less conspicuous forms, as well as ich observed have been 
numerous. 
It is doubtful whether this temporary association between 
Hydra and the Mollusc is of any importance to the latter. Even 
when the Polyp settles on its body and not on its shell (as is some- 
times the case) the Paludina appears to suffer no inconvenience, 
and makes no attempt to get rid of its burden. It is possible, 
on the sweet sere that the Hydra may protect it by devouring 
would-be tes; but of this there is no evidence. In the 
Calcutta sank: awelad Molluses are certainly mo 
visible attack than non-operculate apne. This is the case, for 
instance, as regards the common aquatic Glowworm, which de- 
ys large numbers of individuals of Limnophysa, Limneeus, etc.. 
a se: has been starved for several days in an aquarium it will 
perculate form, but rarely with success. Similarly 
Ohestogeestn bengalensis nsis attaches itself exclusively to non- te 
forms, In the one case the Polyp could i very little re, mig me an 
mt a 
3 
PEE 
namely, drought. As the water sinks in the tank non-operculate 
species migrate to the deeper parts, but Paludina and Ampullaria 
close their shells, remain where they are, and so Soma perish, 
being left high and dry, exposed to the heat of the sun. 
n the other hand, the association is slotted useful to 
Hy ree. The mud on the shells of Paludina taken on floating ob- 
sively, on minute green , as my observations on ae speci- 
mens show. It, therefore, natura urally moves towards spots where 
olyp’s 
1 sg: 1906 this species first oe tee in abundance sg the first pie 
n the Calentta,tanks.. I did not see it during winter. Unlike 
of its Pies, it flourishes in small Gate of water kept without eadiesa 
