Vol. VIII, No. 2.) The Freshwater Fauna of India. 47 
[N.8.] 
to be fixed to an animal which carries it from place to place 
as the snail or the tortoise does, but whereas the Plumatella is 
apparently adapted for this position and no other, the Hislopia 
is able to flourish without any such adventitious aid if neces- 
ry. 
Polyzoa feed on minute plants and animals watted into 
their mouths by means of currents set up in the water by 
Different species of T’emnocephala live in different countries on 
the gills of cray-fish, on the external surface of tortoises, in 
the respiratory chambers of large pond-snails and on the lower 
surface of freshwater crabs. It is in the last position that the 
Indian species (7. semperi) is found. Doubtless the crabs 
carry it into positions in which the insect larvae on which it 
chiefly feeds are abundant. It is very active in its movements 
and catches its prey by means of the finger-like tentacles at 
the anterior end of its body. The little species found on 
Atyidae in Orissa, however, obtains its food in a totally different 
manner. Adhering firmly to the gill-filaments of its host by 
means of a modified posterior sucker, it can suddenly shoot 
out with its mouth, which is situated at the anterior end. of 
the body, a highly muscular proboscis by means of which 
minute organisms are seize 
Another form of relationship that is in a sense a kind of 
symbiosis is that which often exists between the common 
freshwater sponge Spongilla carteri in India (or S. lacustris 
; p . 
instead of being suffocated by the growth of the sponge as 
most of its congeners would probably be, modifies its growth 
ese instances will serve to illustrate the kind of ese 
that are often established between different species of 
