PALUDESTRINA, 143 
The habitat given by Jeffreys between Greenwich and 
Woolwich is now no longer correct. I learn from the 
Rey. J. W. Horsley that this species is nearly, if not quite 
extinct, as far as this country is concerned. He informs 
me that it has not existed for some years in the locality 
given for it by Jeffreys, between Greenwich and Wool- 
wich, but that having migrated down the river, owing to 
the increased pollution of the Thames, it was to be found 
in one small,shallow pond close to the river bank at Erith. 
In September, 1892, Mr. Horsley and I searched this spot, 
which was then dry mud, in vain, and my informant now 
tells me that he has not been able to meet with it on a 
subsequent occasion when he sought it. 
2. P. VENTROSA (swollen) Montagu. PI. VIIL., f. 12. 
Conical, tapering, thin, glossy, semi-transparent ; whorls 6—7, 
rounded ; sfzve pointed; mouth and operculum oval. A. 5 mm. 
B. 34 mm. 
This species swarms in countless thousands in brackish 
marshes on the coasts of Norfolk and Suffolk among 
weed. It is also plentiful in estuaries in England and 
Wales. In Ireland it occurs in Dublin Bay and Larne 
Lough. It is not found in Scotland. 
Var. I. minor (Jeff). Shell much smaller, spire 
shorter. 
Var. II. ovdta (Jeff.). Spire much shorter ; whorls 4, 
more tumid than type; the last exceeds one half the shell. 
Var. III. elongéta (Jeff.). Sometimes 8 whorls, longer. 
