On the Land and b'rcsh- water Mollnsca, d-c. 89 



The Colchester district is watered by three rivers, the 

 Colne and Blackwater wholly in Essex, and the Stour dividing 

 this county from Suffolk. Its boundaries are a line drawn 

 from Bures, through Coggeshall to Maldon, on the west side, 

 and on the east, south, and north the sea and rivers form its 

 confines. 



The names and arrangement adopted in the paper are in 

 accordance with Mr. J. Gwyn Jeffreys' ' British Conchology.'^ 



SPHiERimiE. 



Sph^rium corneum, Linn. — As is usually the case, this is 

 abundant in all the streams and ponds which are suitable. 

 I find it most variable, but I cannot satisfy myself that we 

 possess more than one of the varieties named by Jeffreys. 



Var. fiavescens occurs in the most rapid parts of a brook 

 two miles south of the town. 



S. LAcusTRE, Miill. — Occurs in many ponds, on gravel as 

 well as clay, and it is surprising how they manage to exist in 

 the stagnant and filthy water of some ponds. 



Var. Brochoniana. — This form I find in the remains of the 

 moat of an old manor house at Birch, on Boulder Clay. 



PismiuM AMNicuM, MuU. — Although usually so common, I 

 cannot say that I find it abundantly ; perhaps I have not the 

 knack of searching for it. 



P. FONTiNALE, Drap. — In the marshes of the Colne, &c., 

 but not abundantly. I do not think we have any of the 

 named varieties, but I find the shell to be very variable. 



P. pusiLLUM, Gmelin. — Very abundant in shallow roadside 

 ditches which are dry for months at a time. This also is a 

 variable species, some specimens being nearly round, i.e., 

 more ventricose than usual. 



P. NiTiDUM, Jen. — I do not find it abundant, but stillthe 

 river meadows generally seem to have some in most of the 

 ditches at one part or other. The long grasses growing in 



2 'British Conchology, or an account of the Molhisca which now 

 inhabit the British Isles and the surrounding seas.' Vol. i. Land and 

 Fresh-water Shells. London, 18G2. 



L 



