Mollusca of Bobbit's Hole

110

TWO RANNIES

On 5th November, I noticed that Aggie's coat was in poor condition, and on the night of 9th November she died. She had left her nest and was nose down in the side of the tin. I do not think she died of hunger, as I found an earthworm in the earth in her tin which she could have easily have found and eaten.

Fusspot, in another tin, was well and fat, and on 12th November I released her in a field, and hoped she would find spiders among the dry roots of a tree-topped bank. She was rather upset by the journey, I think, because she bit me for the first time.

I wonder if she still has her grey rump ?

PANSY

DOWNING.

I was delighted to read of Miss Downing's success in caring for the two pygmy shrews, and thought her observations very valuable. Space does not permit a fĂźll discussion of the implications of these observations, but I too, should be very interested to know whether or not Fusspot still has her grey rump.

Most shrews will have moulted by now. Did grey fĂźr grow again on the wound ? Douglas English, who was a keen Student of shrews noted these grey patches, and put them down to poor condition as they were developed in captivity. I have expressed the view elsewhere that they are due to regrowth after wounding, and Miss Downing's acute observations have now borne this out.

PETER CROWCROFT, 26th April, 1955.

THE MULLUSCA OF BOBBITSHOLE INTER-GLACIAL BEDS, IPSWICH

By A. G .

DAVIS, F.G.S.

The fauna is listed in two columns representing two distinct types of deposit, peaty and loamy.

The peaty beds include the dark deposits (detrital mud) underlying the yellow-grey loam. All the deposits were sampled and separate lists made of the shells found in them, but as the differences were so slight it was found more convenient to record the fauna under two headings only. The peaty beds yielded 39 species, 25 of which areaquaticandindicateastreamwithbackwaters running through a marsh. Theterrestialformspresentareallmarsh or swamp dwellers with a few shells washed into the deposit during floods. All survive and become established.

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MOLLUSCA OF BOBBIT'S HOLE

The loam produced 66 species consisting of 35 aquatics and 31 terrestial. The aquatics indicate hard clear water with plenty of Vegetation and terrestial forms belong mainly to the marsh and the rushy areas bordering. No doubt the few Helicoids present were washed into the deposit from nearby wooded ground by floods.

Those species which call for special comment are referred to below. Although thedepositswerewellsampledbythreecompetent observers no trace of Corbicula fluminalis or Potamida littoralis was found and although the fauna is a large and varied one, there are only a few which offer any criteria of age. Three of the species are extinct in Britain and of these Belgrandia marginata and Vallonia enniensis suggest the Bobbitshole sequence is no later than the last inter-glacial.

The fauna is by no means a cold one for in this small area and for a long time, over half the of the known species now living in the county flourished. Since the destruction of the Bobbitshole fauna at the close of the last inter-glacial it has never fully recovered.

Many of the recent species recorded for the county only hold a precarious existence at the present time.

The faunal list has been compiled from the collections made

by Messrs. M. Kerney and H. E. P. Spencer and the writer.

Care has been taken to give the frequencies of the species so that comparisons may be made in future work. The abbreviations used in the list are :— C.—common—100 examples.

Ab.—abundant—over 200 examples.

Acknowledgments :— The writer is much indebted to Mr. H. E. P. Spencer for showing him the Belstead Brook sequence and for help with the sampling.

His thanks are also due to Mr. B. W. Sparks of Cambridge who studied and determined the whole of the Vallonia shells from this site.

Valvata cristata Müller Valvata piscinalis Müller Valvata macrostoma Mörch Pomatias elegans Müller Bithynia tentaculata Linne Belgrandia marginata Michaud Carychium minimum Müller Carychium tridentatum Risso Lymnea truncatula Müller Lymnea palustris Müller

P C 15 1 Ab 33 24 2 8 Ab

L Ab C 45 1 Ab C C 6 C 75

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MOLLUSCA OF BOBBIT'S HOLE

P L Lymnea peregra Müller C C Myxas glutinosa Müller 28 33 Physa hypnorum Linne 1 20 Planorbis carinatus Müller C 89 Planorbis vortex Linne 36 Planorbis planorbis Linne 1 3 Planorbis vorticulus Trochel C C Planorbis leucostoma Millet 17 C Planorbis laevis Alder 26 Planorbis albus Müller 1 Planorbis crista Linne 40 C Segmentina nitida Müller 1 5 Segmentina complanatus Linne 27 65 Acroloxus lacustris Linne C 80 Succinea oblonga Drap 4 40 Succinea pfeifferi Rossm.

28 C Cochlicopa lubrica Müller 1 64 Truncatellina cylindrica Ferru 1 Vertigo antivertigo Drap.

C Ab Vertigo moulinsiana Dupuy 17 66 Vertigo angustior Jeff 5 Ab Pupilla muscorum Linne 7 Acanthinula aculeata Müller 3 Vallonia pulchella Müller 2 Ab Vallonia pulchella var. enniensis Gredler 25 Vallonia costata Müller 81 Clausilia bidentata Ström 5 Clausilia laminata Montg.

5 Helicodonta obvoluta Müller 3 Arianta arborustum Linne 3 Helix memoralis Linne 3 6 Hygromia hispidus Linne 3 C Hygromia libertus Westlund 9 Punctum pygmaeum Drap.

2 15 Discus rotundatus Müller 14 Arion sp 3 Euconulus fulvus Müller 6 Vitrea crystallina Müller 1 Oxychilus cellarius Müller 1 Retinella radiatula Alder 1 50 Zonitoides nitidus Müller 6 12 Vitrina pellucida Müller 1 Limax spp 77 Ab Limux cf. modioliformis Sand 18 JJnio pictorum Linne 1 Unio tumidus Phillipsson 2 Sphaerium corneum Linne C C

MOLLUSCA OF BOBBIT'S HOLE

Pisidium Pisidium Pisidium Pisidium Pisidium Pisidium Pisidium Pisidium

amnicum MĂźller pulchellum Jenyns obtusale Pfeiffer nitidum Jenyns casertanum Poli milium Held moitessierianum Paladulhe personatum Malm

113

10 6 4

4

C 31 2 16 20 4 14 12

N O T E S ON THE SPECIES.

Valvata macrostoma, now living only at Brandon, Very local in marsh drains in S. and E. England. Recorded fossil from the Cromerian at W. Runton, Hoxne, Peterborough and Cambridge.

Pomatias elegans, represented by a fragment high in the section.

It has become rare in the county and is confined to the Chalk area, Bramford, Suffolk.

Belegrandia marginata, extinct in Britain since the last interglacial. Recorded fossil from Brandon and Sutton.

Myxas glutinosa, rare and local in England both recent and fossil. Known from the Cromerian and Hoxne.

Planorbis vorticulus, has been found living at Redgrave Fen, it has restricted distribution in marsh drains in E. Norfolk and Sussex where it is found in association with Valvata macrostoma.

It is a survival from the Cromerian and has been found in the deposits of Swanscombe and Grays A. S. Kennard found it in a Holocene deposit at Knettishall.

Vallonia pulchella var enniensis (Gredler), extinct in Britain. It is the same as V. tenuilimbata (Sandberger) recorded from the Cromerian at W. Runton. Some continental writers give it specific status. Gredler found it in the marshy areas of the S. Tirol and it is known living as far east as the Caucasus. The earliest deposit in which it has been found is the Red Crag of Bawdsey and in addition to the Cromerian (first inter-glacial), it is known from the Clacton and Swanscombe (Second interglacial), also the last inter-glacial deposits at Histon Road, Cambridge. (Sparks 1944.)

Helicodonta obvoluta, not recorded from the county recent or fossil. Only lip fragments were found by Mr. Michael Kerney and their presence indicates flooding of nearby woodland. This species is well known from Cambridge and Grantchester deposits.

Limax modioliformis, extinct in Britain and only known hitherto from the Cromerian of W. Runton.

MOLLUSCA OF BOBBIT'S HOLE 114 Unio tumidus, not recorded living in the county. It is known a fossil from the Stutton Brickearth.

Succinea oblonga, rare in Britian ; it inhabits marshes and of ditches. Not recorded as living in Suffolk, but it has long been known from the inter-glacial of Cambridge.

References :

Ellis, A. E. 1951, Census of the distribution of British Nonmarine Mollusca. Journ. Conch., 23, pp. 171-244.

Sparks, B. W. 1953, Fossil and recent English species of Vallonia.

Proc. Malac. Soc., 30, pp. 110-121.

Sandberger, F. 1880, Ein Betragzur Kenntris der unterpleistocänen Schichten Englands. Palaeontographica, 27, pp.

81-104.

Zeuner, F. E. 1945, The Pleistocene Period, The Ray Soc. Lind.