Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/346

 shell appears to have been smooth; and at its full size about four inches in length : the columella has four folds, and the shell is formed by about six spiral turns, the last of which makes two thirds of the shell, dilating at about its centre, and contracting nearly equally upwards and downwards. The specimens yet seen give no opportunity of judging of the lip, or of the termination of the spire.

The Essex reversed shell, as it has been termed, murrx contrarius Linn. ''Hidt. Conch.'' of Lister, tab. 950, fig. 44. b. c. which is here very abundant, does not appear to be known in any other stratum of the island. The fossil shell, with the whirls in the ordinary direction, is sometimes found in this stratum.

It has been said that the recent analogues of both these shells are found in the adjoining sea. A recent shell is indeed found which very nearly agrees with the ordinarily turned shell in its general characters: but there appears no authority for supposing that the analogue of the left-turned variety has been discovered there.

Among those recent shells, the resemblance of which to the fossil ones of this stratum is such as appears to render a comparison by an experienced conchologist necessary, may be enumerated:

Patella ungarica, Patella militaris, Patella sinensis, (Calyptræa, Lam.) Patella fissura, (Emarginula, Lam.) one or two species of Patellæ, with a perforation in the apex, (Fissurela, Lam.) Nerita glaucina, Nerita corneus, (Natica, Lam.) Turbo terebra, (Territella, Lam.) Murex corneus, Murex erinaceus, Strombus pes pelicani, Cypræa pediculus, with no sulcus along the back, Pholas crispatur, in fragments, Solen ensis, and Salen siliqua, in fragments, Cardium edule, Cardium aculeatum ? beating the size and form of this shell,