156 



JOURNAL, R.A.S. (CEYLON). [VOL. II., PART II. 



SKETCHES IN NATURAL HISTORY: 



DESCRIPTION OF TWO MINUTE NEW 

 FRESHWATER MOLUSKS OF THE GENUS 

 PLANORBIS AND BIT Him A. 



By Edgar L. Layard, Esq., cm.e.s. 



The minute shells here described were first detected by 

 myself accidently : a mass of floating weed taken off the 

 surface of a small tank or pond, about a mile and a half 

 from Hambantota, had been placed in a basin to be 

 examined, to obtain specimens of the next species, and in 

 stirring the floating particles with the hand, a dead specimen 

 of a new Planorbis was found adhering to it. Every atom 

 of the weed now underwent a close scrutiny, and the search 

 produced seven or eight other dead examples, but none living. 



Recourse was again had to the pond, but though a large 

 quantity of weed was collected, and many dead shells found, 

 the habitat of the living creature remained still unknown 

 to me. Later in the year (in the month of June) I was 

 sent to this station, Point Pedro, and during my rambles 

 through the many lanes of this populous village I 

 examined one of the walled tanks which are so common 

 throughout the district ; here, to my delight, plentifully 

 scattered along the edge of the water, were the bleached 

 shells of the Planorbis and the Bithinia of the Hambantota 

 tank. 



Fortunately the drought of several months had reduced 

 the water so considerably as to enable me to examine the 

 decaying vegetable matter at the bottom, and attached to 

 the underside of leaves and sticks were found the Planorbis, 

 while in similar situations, but principally on stones, the 



