of the Land and Fresh-water Shells of Suffolk. 159 
This shell, of which I have taken two specimens in Holbrook 
mill-pond, is of nearly the same shape with H. alba, yet cannot 
be mistaken for it. It agrees also in many respects with Planorbis 
spirorbis of Draparnaud, which is a different species from the 
H. spirorbis of Syst. Nat. as I have remarked in its place, but 
being striated in the transverse direction, a circumstance unno- 
ticed by him, and which he could not have overlooked, it must 
be considered as new ; and I have accordingly honoured it with 
the name of that sagacious conchologist. 
37. Hzrrx FONTANA. Trans. Linn. Soc. vol. viii. p. 193. 
Pond in the Round Meadow, on the estate of John Sheppard, 
Esq. of Campsey Ash; and in Baylham pond. 
In Ramsey decoy-pond, Essex. 
The identity of this species with Nautilus lacustris is I know 
looked upon as certain by some conchologists : I can only say, 
that I have taken some thousands of them without their assuming 
in a single instance the form of that shell. 
. 988.5 HaiIx SOMERSHAMIENSIS. 
H. testa | grisea umbilicata, anfractibus 2 vix 3 reticulatis. 
Habitat in sylvis, rarissima. 
Equal in magnitude to a middle-sized H. alba, which it resem- 
bles in shape ; is of a greyish colour, and curiously reticulated, 
particularly above. 
The only two specimens I huis met with were adhering to 
the under-side of a small decayed branch of oak, in a grove on 
the left-hand side of the road leading from Somersham to Flow- 
ton. 
_ It is perfectly distinct from any species hitherto described ; 
and, from its similarity in shape to Helix alba, has been placed. 
as 
