38 N. Ann ANDALE: T//e Fan //a of Brackis// Po/i(h. [VoL. I, 



invisible to the naked e^^e, by the dark spots due to groups of the 

 Protozoon among the branches of its hyclrorhiza. The Protozoon 

 also occurs independently in the ponds, but rarely. Carchcsium 

 polypinum is just as frequentl}^ found attached to colonies of the 

 Polyzoon Victor clla pavida, but is also common apart from this 

 animal. 



Many other representatives of the Protozoa were taken in the 

 ponds ; they have been submitted, together with other microscopic 

 organisms, to Prof, von Daday, of Buda-Pesth. 



Port f era. — It was in the same ponds that my types of Spongilla 

 Uicustris var. bengalensis (i) were taken in the winter of 1905-6, 

 but in that of 1906-7 this form was entirely replaced by another 

 agreeing closely with Bowerbank's description of his 5. ccrehellata (2). 

 Other specimens, taken near Calcutta and in northern Bengal and 

 sent me from the Chilka Lake in Orissa, convince me that the two 

 forms are identical as regards taxonomic position, being no more 

 than temporary phases of 5. alba, Carter (3), which in its turn may 

 be no more than an Oriental race of the widely distributed 

 5. laciistris. This is a point, however, which I hope to discuss more 

 fully on another occasion. All the sponges in the ponds had per- 

 ished and most had completely disintegrated by the middle of 

 March. 



A notable point as regards these Sponges growing in brackish 

 ponds is the number of animals which take temporary or permanent 

 shelter in their canals. Not only do several species of Amphipods 

 common in the ponds use these canals as temporary resting-places, 

 but an Isopod of distinctly marine facies is common in them and 

 is apparently not found elsewhere in the same habitat. Several 

 small Lamellibranch Molluscs {Corbula, spp.), young individuals 

 of the Actinian to be described later, a larval Dragon Fly, 

 and several species of Chironomid larvae were also found in 

 the canals of the Sponge, while a Cirripede {B. aniphitrite) was 

 taken buried in the substance of one specimen. In my account 

 of 5. lacustris var. bengalensis , I noticed that those specimens of 

 the Sponge which had any definite colour were dark green owing to 

 the presence in them of a filamentous alga. A similar case of ap- 

 parent symbiosis has been recorded from Celebes by Professor and 

 Mme. Weber (4) ; but I am now confident that in such cases the 

 alga should be regarded as a parasite of the Sponge. In keeping 

 certain species of freshwater Sponge, e.g., S. carteri, alive in an 

 aquarium in Calcutta, one of the difficulties to be contended with is 

 the rapid growth of just such filamentous algse, which block up the 

 canals and finall}^ kill the organism. In the Port Canning ponds 

 Sponges infested with the alga are evidently in an unhealthy con- 

 dition and are usuall}^ found towards the end of the season. 



Crelenterates. — Besides the form of Metridiuin schillerianiini 

 (Stol.) to be described in a subsequent paper of this series, I have onh' 

 found one Coelenterate in the ponds, namely the Hydrozoon Irene 

 ceylonensis (5) ; and that only in one pond. The Medusae were 

 abundant from the end of November till the beginniiig of January, 



