BRITISH OYSTERS : OLD AND NEW. 
203 
with the fossil 0 . lamellosa, or the northern 0 . hippopus. I 
do not know Brocchi’s shell as a recent species, and Jeffreys, 
when revising Brocchi’s collection, passed it over as 0 . edulis, 
as might be expected ( Q.J.G.S., 1884). 
VAR. ESTUARII var. novo. 
Hyndman (Rep. Brit. Assoc., 1857, p. 225), remarks that 
oysters were abundant in Belfast Bay from low water to 25 
fathoms, and were taken by line at 45 fathoms off the Copeland 
Islands at the mouth of the bay, the oysters known as “ Carrick- 
fergus Oysters ” attaining a great age. Unfortunately these 
large oysters are no longer procurable, the Belfast Lough not 
paying to fish. The ancestors of these molluscs abound in the 
Estuarine Clays in the Alexandra Dock, Belfast, and in the rich 
shell-banks at Magheramorne, Lough Larne. Bedded originally 
at about 5 fathoms deep in the Thracia convexa zone, as suggested 
by Mr. Praeger, they now exhibit in Lough Larne a thick mass 
of shells. They occur mostly in pairs, but single valves of great 
weight are common, one now in the Belfast Museum weighing 
five pounds, and of corresponding size. A full account of the 
Estuarine Clays and their magnificent fauna may be found in 
Mr. Praeger’s valuable and exhaustive report on the N.E. 
Estuarine Clays (Proc. R.I. Acad, (iii.) v. 2, no 2, 1892). The 
estuarine shells vary in shape, looked at from the outside, from 
ovate, trigonal, or broad-shouldered, to a curved or crescentic 
outline. Inside, this variation is less apparent, which is largely 
due to the spread of shelly growth at the sides. 
As this race, or group, so far as I am aware, has not been des- 
scribed in detail, a brief notice may be useful (plate xiv., fig. 10). 
Sculpture (lower valve) strong, well defined costae traversed 
by broad lamellae, rising into tubular ridges on the costae in the 
earlier growth, these dying out as the shell advanced in age and 
thickness, leaving a plain, non-indentate margin. The shell 
seems to have grown normally to a length of 3-4 inches before 
the alteration in sculpture and lateral deviation ensued. The 
ligamental area varies much, where the shell is much drawn out 
it may be as much as 30 mm. in length and 15 mm. in breadth. 
The scar is large, and in old shells is cut off below from the rest 
of the valve by a thick growth of shelly matter (see Chambrage, 
Of Oysters, p. 8 :) 
