BRITISH OYSTERS : OLD AND NEW. 
201 
average breadth being about 3J inches (85 mm.), and are nearly 
always ovate-oblong in outline, beaks but slightly projecting, 
lower valve convex, upper one slightly so ; lamellae rather pro¬ 
minent. The lower valve exhibits well defined to strong ribbing, 
the costae regular and co-equal in size to the interspaces, becoming 
slightly vaulted at the intersection of the yearly shoots ; margins 
entire. The ligamental area is moderately broad, hinge nodules 
well marked, colour inside white to purple in blotches. Scar 
lunate, (plate xiii., fig. 8). 
A very old shell from a deposit of some antiquity at Hillswick, 
in the Shetlands, exhibits the pear-shaped interior of the shell, 
and the accretionary growths seen in the Irish Estuarine types, 
and the lateral expansion of the ligamental area which seems 
to be characteristic of age. 
Mr. Garstang, {Viet. Hist. Essex, p. 81, 1903) says “ numbers 
•of dead shells occur where living animals are seldom if ever 
found, I often think that many of these dead shells* are of a 
more elongated shape than the modern living varieties/’ 
The Manx oyster fishery is now practically extinct. I owe to 
the Rev. S. N. Harrison, of Ramsey, two or three examples ob¬ 
tained from deep water by the fishing boats, in 15-20 fathoms off 
Ramsey, and dead valves may be found on the beach. They 
represent a strong and large shell, length 5 inches, breadth 
inches. The interior is a dull, chalky white, like most of 
the other members of this series (plate xiv., fig. 9). 
Prof. Forbes, in describing in the Mag. N. Hist. 1839, p, 
217, a shell bank five miles off Ballaugh, refers to the oysters he 
dredged there ; they were never in great numbers, but very 
large, muscular and thick shelled ; half-grown specimens were 
rare, and he had never seen a very young shell. The oysters 
seemed to be the aged survivors of some former colony. Most 
-of the examples were dead shells ; the living generally 
perforated by Cliona. 
Wexford shells, both raised beach and deep sea, belong to 
this group. The shells from the early gravels at Blackwater 
•closely resemble the smaller valves I have from Cnoc-Sligeach, 
Oransay. The same may be said of the shells in the limestone 
•drift in Ballybrack Bay, as of those found at Malahide, near 
Dublin, between tide marks. 
*Such as are found in the Pleistocene peat in the River Orwell. 
