XIV.— THE FAUNA OF BRACKISH PONDS 

 AT PORT CANNING, IvOWER BENGAI^. 



Part VI. — Observations on the Polyzoa, with further 

 Notes on the Ponds. 



By N. Annandale, D.Sc, Officiating Superintendent, 

 Indian Museum. 



Thanks to the kindness of Mr. D. Hooper, I am now able to 

 give figures representing approximately the maximum and minimum 

 salinity of the water of one of the ponds during the present 3^ear. 

 A sample taken on May 25th (about three weeks before the be- 

 ginning of the rainy season) from the pond in which the hydroid of 

 Irefie ceylonensis was found, contained 22'88 per thousand of 

 saline residue, while one taken from the neighbourhood of the same 

 pond on July 9th contained only 9*82 per thousand. At the latter 

 date the whole area containing the ponds was flooded and the 

 river embankment had broken down in their vicinity. It will be 

 remembered that the water of the same pond contained I2'i3 per 

 thousand of saline constituents in December, and 20*22 per thousand 

 in March. By an unfortunate mistake the former figure is mis- 

 quoted as 0'22 per cent, on pp. 69 and 82 of pt. i of these 

 " Records." 



A factor in the distribution of the pond fauna to which at- 

 tention was not paid in my preliminary account (pp. 35 — 43) is the 

 bore on the Matla river. Mr. Hodgart, Zoological Collector in the 

 Museum, tells me that at this time of year it is often so strong that 

 people in the neighbourhood of breaks in the embankment are 

 obliged to take refuge on its approach in the upper storey of the 

 nearest brick house. The bore of course onh^ affects the ponds 

 when the embankment is broken and they are therefore put in 

 communication with the river, but on such occasions it must bring 

 into them many organisms from the neighbourhood of the open 

 sea. Collections made in the ponds during the present month 

 (July, 1907) include specimens of several forms not hitherto taken 

 in the tanks, notably one of a species of the Sipunculid genus 

 Physcosoma, which was found in the mud. They also include 

 most of the forms already taken, notably Metridium schillerianum 

 var. exul in great abundance and the Polyzoa Victorella pavida 

 and Bowerhankia caudata , both in interesting stages ; Irene cey- 

 lonensis was not seen. 



