1867.]' Contributions to Indian Malacology. 51 



Contributions to Indian Malacology, No. VIII. List of Estuary shells' 

 collected in the delta of the Ibawady, in Pegu, with descriptions 

 of the new species. By William T. Blanford, A. R. S. 31., F. G. S. } 

 Cor. Mem. Z. S. &c. 



[Received 14th November, 1866.] 



A short visit to Calcutta, and access to various works on conchology 

 wliich have, for some years past, been beyond my reach, have enabled me 

 to prepare the following list of the species of mollusca collected by 

 me in the Pegu delta during the early portion of 1862. In March 

 and April of that year, whilst engaged in the Geological Survey of 

 the country south of Bassein, I was compelled to traverse the net • 

 work of creeks which intersect the Irawaddy delta in every direction, 

 and, in so doing, I had many opportunities of searching for the various 

 mollusca inhabiting the channels of brackish and salt water. 



The western portion of the Irawady delta south of Bassein is of 

 peculiar character. Instead of the endless alluvial flat which is usually 

 alone met with near the mouth of large rivers, the country is frequently 

 undulating, and even, in places, hilly ; the hills being surrounded by 

 plains of alluvial soil intersected by tidal channels. llock not 

 unfrequently occurs in these creeks, and affords a habitat for many 

 mollusca which are not met with in the usual muddy flats. 



The Bassein river itself, one of the numerous mouths of the 

 Irawady, like the Mutlah and other great channels of the Ganges 

 delta, is at present rathei' an. arm of the sea than a river; as it 

 receives no fresh water directly from the Irawady except during tho 

 height of the rains. In the cold weather the water is perfectly salt 

 for many miles above the mouth, and marine animals abound. Thus 

 for many days, during the time I was traversing the neighbourhood, 

 the water swarmed with Medusce. The volume of fresh water which 

 pours into the Bassein river can at no time be very large, for the mollus- 

 ca which inhabit the southern side of Negrais Island, some distance 

 within the mouth of the river, are typically marine, comprising species 

 of Parmophorus, Triforis, Trochus, Chama, &c, and not including any 

 of the usual estuary forms Assiminia, Amphibola, Neritina, &c, whilst 

 at Poorian Point and Pagoda Point, the two headlands Avhich form 



