MOO bia ON. oc OME AQUATIC OLIFEGOCHAE LE 
WORMS COMMENSAL IN SPONGILLA 
CAR EERT. 
By J. STEPHENSON, M.B., D.Sc. (Lond.). 
I recently received from Dr. Annandale, of the Indian 
Museum, a specimen of a form of Spongilla cartert, Bwk., taken 
at Bheemanagar, Travancore, and sent by the authorities of the 
Trivandrum Museum to Calcutta. The specimen was stated to 
contain a number of aquatic Oligochaeta, and it was these which 
I undertook to examine. 
The worms were found to be very numerous; they could be 
obtained in numbers by teasing any small fragment of the sponge, 
and could be picked out from the disintegrated portions of the 
sponge at the bottom of the bottle. 
Thirty-eight specimens taken at random were prepared and 
mounted for microscopic examination; some were mounted un- 
stained in glycerin and potash, some unstained and some stained 
in balsam. A first inspection showed that there was one specimen 
of Pristina longiseta, Ehrbg., and that all the rest belonged to the 
genus Nats. 
As was to be expected, a certain number of the specimens 
were distorted in shape, and others had their dorsal setae entirely 
or almost entirely broken off. The rest were classified under the 
high power into three groups, as follows :— 
(i) Forms without eyes, with obviously forked needles in 
the dorsal bundles. 
(ii) Forms without eyes, with dorsal needles showing only 
a very fine forking, or in which forking was not 
evident. 
(iii) Forms with eyes. 
All the individuals of groups (ii) and (ili), and a number of 
those of group (i) (which were the most numerous), were submitted 
to detailed examination with the oil immersion lens. 
As is well known, the usual mode of reproduction in the 
Naididae is the asexual, by fission. Sexual reproduction seems, in 
the majority of forms, to take place only at certain seasons of the 
year, and is comparatively rare; consequently the sexual organs 
have as yet been described only in a minority of the forms 
included in this family. It can hardly be doubted that descriptions 
of these organs, if they could be obtained, would give very great 
help in the task of discriminating the various species. | 
