|
Type |
Samples |
Individuals (approx) |
Details |
| |
|
|
|
|
L |
96 |
1500 |
Loose soil and tree and other surface debris sample of average dry
weight of about 400 gm generally from two monads (1 km squares) per
tetrad |
|
R |
136 |
4100 |
A five minute collection from a roadside in practically all monads in
which there was a road |
|
T |
33 |
1000 |
Collections over about 20 minutes from a railway in most monads having
one |
|
V |
8 |
135 |
A set of special samples from the base of stone walls in monad SP0849 |
|
W |
21 |
21 |
Collections over about 20 minutes from walls (mostly stone) and
retaining walls in each monad having a significant number of stone walls. |
|
X |
87 |
2050 |
Additional collections from the surface, under stones and logs from
most monads having less than two other samples. |
|
(Sum) |
381 |
9100 |
|
|
Table 1. Details of sampling – see text. |
Results
The number of species discovered during this limited survey was high,
particularly in the north-west (Cleeve Prior and the Littletons) and in the
south-east (Broadway). Figures 2 to 5 show the distribution maps and histograms
for the number of species both per monad and per tetrad (2 km by 2 km squares).
The number of species varied from 2 to 22 per monad and from 6 to 31 per tetrad.
Cleeve Prior and the Littletons area was significantly richer in snails than
elsewhere with tetrad SP0646/SP0747 being very significantly richer.
Species accounts
Names, size ranges, status, British distributions and a few other details
were taken from Kerney, 1999.
Drawings
These were all based on specimens from the survey area. Where a single
drawing is given per species, this is life size. Elsewhere two drawings are
given, the left-hand one being enlarged and the right-hand one, in the circle,
being life size.
Distribution maps
A symbol on the map denotes at least one individual (shell or live animal)
was found in the monad during the survey. A black square indicates that at least
one individual was found in an area not usually subject to flooding, a black
triangle indicates that individuals found in the monad were all in samples from
areas normally subject to flooding.
Acknowledgements
I would like to thank Rosemary Hill for confirming some identifications and
Harry Green for arranging this. Also Alison Ward, Betty Ballard and John Tilt
for help in colour descriptions.
Reference
KERNEY, M. 1999 Atlas of the Land and Freshwater Molluscs of Britain and
Ireland. Harley Books.
The 48 species accounts and distribution maps follow.
