Fossil Voles

T H E CRAG

MAMMALIA

155

for determination, is not present; also part of the inner side of the pedicle has been similarly lost. The front of the pedicle appears to have sloped in line with the facial bones and not to have been projecting, at an angle, as is usual, thus curving into the skull line ; there is a deep crescentic groove at the back.

The antler is at a slight angle with the pedicle and the burr is very slight.

The other bone is a calcaneum (Heel bone), which, in view of the great rarity of contemporary deer remains in the crag, and from its having been found close to the other specimen, may almost certainly have belonged to the same animal.

These important fossils and the circumstances of their discovery were reported to the Museum by a member of the Surveyor's Department at Felixstowe.

FOSSIL VOLES THE Ipswich Museum has received from Mr. R. A. Long some interesting vole teeth from Easton Bavents and Covehithe. The Easton Bavents remains consist of two first lower molars, a first and a second upper molar, two upper incisors and one lower, with some fragments. The lower molars have each two roots and the small enamel islet on the anterior loop on the crown which is characteristic of the enamel pattern of that tooth in Mimomys pliocaenicus Forsyth Major, in adult stages of wear. The first upper molar has three roots and is also attributable to M. pliocaenicus. The second upper molar has only two roots though the base is damaged and it might have had a third : all that can be said of it is that it is of some species of Mimomys. The Covehithe specimen is a single first lower molar attached to a portion of the lower jaw : the tooth certainly has roots but they cannot clearly be seen. The anterior loop of this tooth shows no signs of the complexity which is typical of M. pliocaenicus, M. savinii Hinton, and M. majori Hin ton, and while it is impossible to dogmatise about a single tooth, it would appear that it should be attributed to M. intermedius, Newton. M. pliocaenicus has alreadv been found in Suffolk (Trans. II, pt. 1, p. 19, 1932) but no remains of M. intermedius have hitherto been recorded from the county though it has frequently been found in Norfolk.

M. pliocaenicus is the earlier of the two species : it has been found in the Norwich Crag in Norfolk and Suffolk (in association with

156

FOSSIL VOLES

the smaller M. newtoni Forsyth Major) and in the Weybourne Crag at East Runton (with M. savinii, M. intermedius and M. ma M. intermedius has been found but rarely in the Weybourne Crag at East Runton but is one of the most abundant fossils of the Upper Freshwater Bed there : it is also found in the Upper Pliocene or earliest Pleistocene deposits of Hungary.

Figl4~ Fis /.

Fi9. 2.

5 mm

Mimomys was a relatively large vole, most species being about as large as the modern water vole (Arvicola) of which it seems to be the direct ancestor. The form of the skull and the enamel pattern of the teeth are very similar to those of Arvicola but in Mimomys the cheek teeth develop roots, in the adults in the earlier species and in old age in the later : in Arvicola of course the cheek teeth are rootless and continue growing throughout their owner's life into extreme old age. In Norfolk remains of Mimomys have been found showing the gradual development of this rootlessness, the growth of the molars ceasing and roots being developed at later stages in the life of the individual as the genus is traced onwards from the earlier to the later horizons. Finally there comes a moment when no signs of roots can be seen and the remains in question have to be referred to Arvicola. Thefiguresshown above are drawn with the aid of a camera lucida and show :— FIG. 1.—The outer side and crown of afirstleft lower molar from Easton Bavents. The enamel islet on the anterior loop can clearly be seen as can the corresponding small re-entrant on the outer side. The posterior root is more or less complete and well developed, the other broken.

FIG. 2.—The same aspects of thefirstleft lower molar from Covehithe. The outer edge of the anterior loop is somewhat water worn but there is no trace of the enamel islet nor of the

157

FOSSIL VOLES

fourth re-entrant on the outer side. The roots cannot be seen from the side as the lower portion of the tooth is embedded in a fragment of bone but the end of the posterior root can be seen from below.

FIG. 3.—The inner side of the first right upper molar from Easton Bavents. The anterior root is complete and well developed : the two others have been broken but there are clear indications of both.

FIG. 4.—The inner side and base of the second right upper molar from Easton Bavents. T h e posterior root is more or less complete, another, and that nearly closed, can be seen. C.

STRATIGRAPHY AND FAUNA OF THE EASTON BAVENTS CLIFF SECTIONS, NEAR SOUTHWOLD, SUFFOLK BY

G.

P.

LARWOOD,

B.SC.,

F.G.S.

AND A .

J.

MARTIN.

IN 1952, Mr. R. A. Long of Lowestoft drew attention to the recent erosion of the cliffs at Easton Bavents, Suffolk, and it was realised that an excellent opportunity was provided to re-examine the entire sections from Southwold to Easton Broad, last fully described between 1875 and 1878 by W. Whitaker. Accordingly detailed observations of the exposures were made on a number of occasions in September, 1952, and March, 1953. T h e present paper is an attempt to describe the observed sections in detail and to resolve some of the apparently conflicting views expressed by previous workers as to the true limits and origin of each division within the succession exposed.

DESCRIPTION

OF T H E

SECTIONS

(See diagram facing page 160)

It was found that the beds exposed in the cliff sections could be grouped into three major units, the uppermost being the more variable. T h e grouping adopted was as follows :— 3.—Uppermost sands with gravels.

2.—Variable blue-grey clay unit.

1.—Basal sands with or without shells and shell beds.

T h e lithology of each unit is described in the order of deposition.