472 Records of the Indtan Museum. [VoL. XT, 
Owing to the more robust form of this sponge it has been 
possible to extract larger and more complete pieces, which exhibit 
its manner of growth in the burrows of Cliona. The specimens 
were found in the centre of a piece of coral about 4 cm. thick. 
No part of the sponge was visible on the surface of the coral. It 
consisted of irregular cylindrical, ramifying and even reticulate 
masses, the component branches of which were about 2 mm. thick. 
The colour was deep purple-brown, except at the extremities, 
where it was much fainter, if not altogether absent. ‘The surface 
was for the most part smooth, but crater-like pits surrounded by a 
particularly dense zone of spicules occurred sparingly. Large oval 
cells containing brown pigment-granules could be detected in the 
choanosome. At many points the greater part of the ectosome 
was entirely concealed by spicules, mostly spherasters. Oxyasters 
occurred sparingly in the choanosome. 
The most interesting feature of the sponge, however, consisted 
in little tentacle-like club-shaped branches (pl. xxxiv, fig 4a) the 
free extremities of which were densely covered with spherasters, 
while the cylindrical portions were bare of spicules or almost so. 
In some cases the tips of these branches were in contact with the 
surface of other sponges or of tubes constructed among them by 
Polychaete worms. Wherever this occurred the tip was splayed 
out and, if the sponge touched was a Cliona, the latter was pro- 
tected by a dense layer of its own macroscleres and by a chitinous 
sheath (pl. xxxiv, fig. 4). Some cases were seen in which the 
expanded tip of a branch of the Chondrilla was actually spreading 
out in a thin, colourless film over the surface of another sponge or 
of a worm-tube. We have here proof of actual aggression on the 
part of the Chondrilla, and evidence of the methods by which 
Cliona defends itself against such aggression. This subject is dis- 
cussed later (p. 476). In every case, on the other hand, in 
which Stoeba plicata is the sponge attacked by this or other 
species of Chondrilla its ectosome, with the microscleres abundant 
in that part of the sponge, had disappeared where the attacking 
sponge had covered it. 
Part II.—BIOLOGICAL,. 
The large proportion of the sponges referred to in this paper 
were found in two small pieces of dead Madreporarian coral, 
neither weighing more than a few ounces. One piece came from 
the Andamans, the other from the Mergui Archipelago. The 
former is a portion of a somewhat larger specimen examined by 
Carter many years ago and described by him in his account of the 
sponges collected by the late Dr. John Anderson. He found in it 
examples of no less than 8 species of sponges and yet it is clear 
that his examination was not exhaustive, for (in addition to the 
majority of the species he noticed) the fragment now in the Indian 
Museum contains at least four others. ‘There seems to be a stage 
in the decay of the more solid Madreporarian corals at which their 
