LEDA-MYALIS BED. 
193 
the bed with Mya truncata, so often alluded to by diffei’ont 
authors, and first mentioned by Trimmer in 1845.* The section 
on the east side of the Gap is :— 
Soil 
Contorted Drift 
Leda-myalis Bed 
Upper Freshwater Bed 
Forest-bed (estuarine) 
Contorted stony loam, marl, and sand 
Fine false-bedded sand with thin seams 
of loam, and gravelly base full of 
shells - - - - - 
Freshwater sand and peaty loam ; full 
of shells . . _ - 
Weathered loam with roots and frag¬ 
ments of marine shells (Eootlet Bed) 
Feet. 
8 
30 
15 
1 
? 
The following species of mollusca were found in the Leda- 
myalis Bed; but here, as at Sherringham, the exposure has been 
obscure for several years :— 
Buccinum undatum, Linn. 
Littorina littorea, Linn. 
-rudis, Maton. 
Purpura lapillus, Linn. 
Trophon antiquus, Linn. 
-reversed var 
Natica catena ? Da Costa. 
X Astarte borealis, Chem. 
The species marked x were found in the position of life with 
the valves united. Trimmer also mentions Tellina ohliqua, Mya 
arenaria, and Natica helicoides from this spot. Besides these 
marine species, the bed contains a good many freshwater forms, 
evidently washed out of the sands two or three yards away. 
Under Wood Hill a few scattered shells have also been found, 
including a single valve of Tellina ohliqua ; though the bed is 
generally from 10 to 15 feet thick, fossils are rare and confined 
to the base. 
To the south-east of Wood Hill, the Leda-myalis Bed can be 
traced as far as Cromer with the same lithological character, but 
no fossils have yet been found in it. During some alterations to 
the cellar of a house on Cromer sea-wall the sands were well 
shown, though neither tlie top nor bottom was exposed. Be¬ 
tween Cromer and Kirby Hill, unfossiliferous sections can be 
seen whenever the cliff' is free from talus; but the bed is 
becoming attenuated, and towards Beck Hithe it appears to thin 
out altogether against the Boulder Clay. 
Though the horizon may be represented by unfossiliferous 
sands in several places, it has not been recognized elsewhere. 
The deposit at Mundesley, formerly correlated with the Leda- 
myalis Bed, is now known to belong to the Forest-bed, and to 
underlie the Upper Freshwater Bed. The overl^dng sands 
probably form part of the Arctic Freshwater Bed. 
Cardium edule, Linn. 
Cyprina islandica, Linn. 
xLeda myalis, Uouth. 
X Mya truncata, Linn. 
Mytilus edulis, Linn. 
Ostrea edulis, Linn, (fragment). 
Tellina balthica, Linn. 
* On the Cliffs of the Northern Drift on the Coast of Norfolk, between Weybourne 
and Happisburgh.— Quart. Journ. Geol. Soc., vol. i., p. 218. Proc. Geol. Soc., 
vol. iv. p. 435. 
E 60798. XT 
