1922.] Fauna of the Chilka Lake : Observations in Rambha Bay. 691 



coated with Spongilla alba. In the dry season of 1919-20 it died down, as it also 

 did in a small pool of nearly fresh water on Barkuda, but dead sponges containing 

 gemmules were common on the under side of stones at the edge of the lake. At the 

 end of June, 1920, when the water had again become much salter, gemmules, which 

 showed no tendency to germinate, were common in the same position and also on the 

 surface of the bay. A single young sponge was, however, found on Potamogeton 

 on June 26th. 



CoEIvENTERATA. 



The following species of coelenterates were found in Rambha Bay in 1913 and 

 1914 : Gyrostoma glaucum, Phytocoetes^ chilkaeus, Pelocoetes exul, Halianthus limnicola, 

 Edwardsia tinctvix, Virgularia sp., Acromitus rabanchatu, Dicyclocoryne filamentata and 

 Bimeria fluminalis. Of these species, all of which but the Virgularia were originally 

 described by myself, the first five are, in a wide sense, Actiniaria, the sixth is an 

 Alcyonarian, the seventh a Rhizostomatous medusa, while the eighth and ninth are 

 gymnoblastic Hydrozoa. Most of the species belong to marine genera and all to 

 marine families, but Phytocoetes, Pelocoetes and Dicyclocoryne have been taken only in 

 brackish water. 



In 1919-20, the only species included in this list that were observed were 

 Halianthus limnicola, Acromitus rabanchatu^ Dicyclocoryne filamentata and Bimeria 

 fluminalis. These I will discuss in order, but first I must put on record additions to 

 the coelenterate fauna of the bay. On August 14th, 1919, Major Sewell took, in a 

 sample of water from the surface, a single medusa of Campanulina ceylonensis 

 (Browne) of the typical form. This medusa was obtained in the outer channel of the 

 lake in 1914, but not in the main area. In the neighbourhood of Calcutta the 

 hydroid is abundant in canals of brackish water at the beginning of and just before 

 the rainy season and produces medusae in great abundance in water having a low 

 specific gravity. Both hydroid and medusae disappear when the specific gravity 

 sinks below 1*006 C. (corrected to standard temperature of 15°C) owing to increase in 

 the rainfall. In the Gangetic delta this usually takes place about the end of July- 

 On June 26th, 1920, numerous specimens of the medusa Phialidium cruciferum, a 

 form hitherto known only from the outer channel of the Chilka Lake, were taken in a 

 tow-net round Barkuda. In one of them one of the radial canals branched a short 

 distance from the proximal extremity. The branch, which reached the edge of the 

 umbrella, bore an imperfectly formed subsidiary manubrium. On the inner surface 

 of the umbrella the Protozoon Trichodina was abundant. The medusae were feeding 

 on pelagic fish-eggs, which were observed in the stomach of several. 



1 Mr. T. A. Stephenson has- just published an important paper on the classification of the Actiniaria 

 (Quart. Joitrn. Mic. Sei. LXIV, No. 256) in which he discusses the brackish-water species assigned by 

 me to the Sagartiidae, subfamily Metridiinae. He considers these species as constituting a new 

 family (Diadumenidae) with Sagartia schilleriana Stoliczka, as type, under the name Diadumene (gen. 

 nov. ) schilhriana. He further separates my Phytocoetes chilkaeus from P. gangeticus generically under 

 the name Mena (gen. nov.) chilkaea. As to the generic distinction of Stoliczka's species he is undoubt- 

 edly right, but J am not at present prepared to follow him in the other changes suggested. 



