42 



NOTES ON SOME BKITISH NON-MAKINE MOLLUSCA. 



By A. W. Stelfox. 



Bead 12th January, 1912. 



PLATE II. 



1. Planorbis vorticulus, Troschel. 



Ill 1908 Mr. A. S. Kennard recorded this species in a recent state 

 from Pevensej' in Sussex, from examples collected by the late 

 P. Ruiford in Pevensey Level (Proc. Malac. Soc. London, vol. viii, 

 p. 46). Mr. Rufford was unaware of the specific identity of these 

 shells, lie having considered them as P. vortex. As the exact locality 

 from which the shells came is unknown, !Mr. Kennard urged me to 

 keep a sharp look out for it when in Sussex. It was not, however, 

 until Septeuiber, 1911, that I was fortunate enough to meet with it. 

 Upon this occasion a party consisting of L. E. Adams, E. Collier, 

 R. J. Welch, C. E. Wright, and myself were working the district 

 round Lewes in East Sussex. P. vorticulus was taken by us in five 

 different stations, viz., in the moat of Pevensey Castle; in the 

 marshes east of Pevensey ; in the marshes between Pevensey 

 and Eastbourne; in those east of Lewes (near Stoneham Farm); 

 and in those north-west of Lewes, beyond the Abbey, and along 

 the south side of the Cockshute liiver. In all the above 

 stations, except the first, P. vortex occurred also, and there can be 

 no doubt that P. vorticulus has been passed over as the young of 

 /'. vortex. In most of the localities P. vorticulus was scarce, one 

 example occurring to about fifty of P. vortex. In its habits it rather 

 resembles P. fontamis than P. vortex, since it appears to be almost 

 confined to the extreme edge of the drains, preferring tlie grassy 

 margins to the open water of the centre. When this vegetation is 

 disturbed the shells float off, and remain upon the surface of the 

 water for some time. Mr. Kennard informs me that he has taken it 

 alive at Thorpe near Norwich, East Norfolk, and that it also occurs 

 in the Holoeene peat near Ely (example in Sedgwick Museum, 

 Cambridge). Since no illustration of this species has yet been given 

 in this country, Mr. Welch has kindlj^ photographed it (Fig. 22) 

 beside P. vortex (Fig. 23). 



2. Valvata macrostoma, Steenbueh. 



At my first unsuccessful attempt to obtain Planorhis vorticulus in 

 Pevensey Level I was compensated by finding the present species 

 (Kennard & Stelfox, Proc. Malac. Soc. London, vol. ix, p. 123, 1910). 

 Upon returning to Sussex in September, 1911, I obtained further 

 examples in the marshes near Stoneham Farm, east of Lewes, also in 

 East Sussex, and it was taken sparingly by our party in the marsh 

 east of Pevensey. Like Valvata piscinalis (Miill.), this species is 

 generally found on the bottom or sides of the drains. In the mar.sli 

 at Lewes I found the three British species of this genus in association, 

 but only in one spot. In many places F. cristata and V. piscinalis 



