var. radiata occurred with the type at Belfast, Lough Foyle, and Magheramorne.

N. nitida, G. B. Sowerby. Sparingly distributed in the Lough Foyle beds. I obtained it at both Eglinton and Limavady Junction.

* Leda minuta, Müller. Grainger found a single valve of this species in the Belfast bed. This specimen was erroneously recorded in the supplement to Mac Adam's Paper as Nucula oblonga (L. pernula).

Pectunculus glycymeris, Linn. Is not uncommon in the Magheramorne clay.

*Lepton nitidum, Turton. A single complete specimen of this little shell is now recorded from the Belfast bed. It was found by Canon Grainger, during his explorations, but lay unnamed in his cabinet till after the publication of his Paper, when it was determined by Dr. Jeffreys. The shell has since been kindly examined and confirmed by Mr. J. T. Marshall.

[Arca tetragona, Poli, recorded from Alexandra Dock by the writer, was an error.]

Montacuta bidentata, Montagu. This little shell is one of the most characteristic species of the estuarine clays, being found, usually abundantly, at every station except those where the Scrobicularia zone only is present. The bathymetrical range is given by Jeffreys as 10 to 70 fathoms, but the depth in which it formerly abounded in local waters was presumably less than 10 fathoms. It appears to be now quite extinct on North of Ireland coasts, a few dead valves in one or two localities being the only recent records.

M. ferruginosa, Montagu. Occurs in the Thracia clays, but much more sparingly than the last. Limavady Junction was the only station where it was common. It also occurred at Larne, Alexandra Dock, West Bank, Holywood, Newtownards, and Kircubbin. Like the last, it is very rare locally in a recent state, and has not been taken alive.

Lasaa rubra, Montagu. A number of valves occurred in the black sand overlying the estuarine clay at the section in the railway cutting at Larne.

R.I.A. PROC., SER. III., VOL. II.

X

Kellia suborbicularis, Montagu. Has occurred to Bell and myself at Magheramorne; I also obtained one valve in the Kircubbin

bed.

Lucina borealis, Linn. Is abundant in the deposits at Magheramorne, Kircubbin, and Downpatrick, and rarer at Belfast and Larne ; very rare in the Lough Foyle and Greenore beds. The shells from almost all the beds are of small and uniform size, having a diameter of about inch; but the Belfast specimens were fullgrown, and at Magheramorne, among myriads of small examples of the size mentioned, a few tumid shells of 1 inch diameter

occur.

Axinus flexuosus, Montagu. A characteristic upper clay shell, which is rare in our present waters. The deposits at Limavady Junction, Magheramorne, Alexandra Dock, and Downpatrick, yielded fine specimens in profusion, and it occurred in several other beds. Cyamium minutum, Fabricius. Grainger and Stewart have both recorded this small shell as occurring sparingly at Belfast, and Stewart from Magheramorne also. To me it occurred at Larne, where it was locally abundant, and sparingly at Magheramorne, Kircubbin, Downpatrick, and Greenore.

Cardium echinatum, Linn. This fine and well-known shell is abundant in the Thracia clays at Belfast, as already testified by Grainger and Stewart. It occurs, but in less profusion, in the deposits of Lough Foyle and Magheramorne.

C. exiguum, Gmelin. Widely distributed, being present in almost every deposit examined, but is finer and more abundant in the Thracia than in the Scrobicularia zone. The clays at Magheramorne and Larne are replete with fine examples.

C. nodosum, Turton. Single valves occurred at Bann, Alexandra Dock, and West Bank. Stewart obtained a single specimen at Magheramorne only.

C. edule, Linn. This ubiquitous species is as abundant in the estuarine clays as it is at the present day. Though more plentiful in the littoral deposits, it also occurs throughout the deep-water clays. Few specimens were of more than average size.

var. rustica occurred at Alexandra Dock with the typical form.

C. norvegicum, Spengler. At Belfast only, where its occurrence has been noticed successively by Grainger, Stewart, and the writer. It is very sparingly diffused in the Thracia clay there. Two single valves, of fine size, were all that occurred to me.

Cyprina islandica, Linn. This large shell, abundant on our coasts at the present day, is conspicuously absent from the estuarine series. One complete specimen at Spencer Basin (Stewart) and another and two single valves at Alexandra Dock (Praeger) are the only indications of its existence. The conditions then obtaining would not, however, appear to have been unfavourable, for my specimens are of at least average size, and one of the single valves has a breadth of 5 inches.

Venus exoleta, Linn. Single valves only, at Alexandra Dock, Newtownards, and Magheramorne, sparingly.

V. lincta, Pulteney. Long recorded from the Belfast deposit, but in very sparing numbers. I obtained a few valves at Larne also.

V. fasciata, Da Costa. Occurs at Magheramorne, and a very few valves were obtained at Alexandra Dock.

V. casina, Linn. At Magheramorne only, where examples of fine size are somewhat abundant. Like some other estuarine clay species, while the habitat usually assigned to it is a sandy bottom, the clays show that it can flourish on a bottom entirely muddy.

V. ovata, Pennant. Noted by Stewart as frequent at Magheramorne. To me it occurred only very sparingly there, as also at Eglinton and Larne, but was more common at Kircubbin. In our present waters it is abundantly distributed, and its rarity and starved size in the estuarines show that a muddy bottom is unfavourable for its growth.

V. gallina, Linn. Widely distributed, but usually in sparing numbers and of small size. Was abundant at Alexandra Dock, attaining an average breadth of inch. In some localities on our coasts recent examples attain a breadth of 14 inch.

var. laminosa and var. gibba occur occasionally, with forms intermediate between them and the type.

Tapes aureus, Gmelin. Is present in all but the Scrobicularia clays. Apparently much rarer now in the same area.

var. ovata. Stewart records this variety from Belfast and Magheramorne, at both of which stations it also occurred to me.

T. virgineus, Linn. Noted in Hyndman's first Belfast Dredging. Report as common in the alluvium"; but this must have been a mistake. Neither Grainger nor Stewart found a trace of it; and three single valves at Alexandra Dock is my only record of it from the Belfast deposits. At Magheramorne it occurs in great abundance, and of abnormal size, often attaining a breadth of 24 inches. It was present in less numbers in the Lough Foyle deposits and at Larne.

T. pullastra, Montagu. More generally diffused than the last species, but absent from the strictly littoral deposits; also attains a very large size.

T. decussatus, Linn. Characteristic of the Scrobicularia clays, but of occasional occurrence in the Thracia zone also. At Alexandra Dock it was present in the lower clay in countless numbers, but of small size; while in the upper clay it was rare, but of large dimensions. It is absent from the Lough Foyle beds, and rare in those of Larne Lough; also occurred at Kircubbin, Downpatrick, Greenore, and Dundalk. Is now almost extinct in the district.

Lucinopsis undata, Pennant. Its abundance and large size in the Belfast deposits have been noticed by all the writers on the subject; it is one of the most characteristic species of the Thracia clays there. To me it occurred in profusion at Alexandra Dock and West Bank, and sparingly, also, at Limavady Junction and Magheramorne. This shell has now entirely deserted Belfast Lough, and appears very rare on North of Ireland shores.

Gastrana fragilis, Linn. This species has been already referred to on a previous page. One large valve was obtained at Downpatrick, and a small one at Kircubbin. In a recent state, Lough Swilly. in Donegal, appears to be its only station on the eastern or northern shores of Ireland. The European distribution of the species is essentially southern.

Tellina balthica, Linn. Was present in varying numbers at almost every station. At Alexandra Dock its distribution was very marked; it was present in the surface clays in large numbers, quite absent from the Thracia zone, and in the Scrobularia clays again appeared in profusion, many examples measuring over an inch in breadth.

T. tenuis, Da Costa. A very few examples at Larne and Alexandra Dock. Grainger and Stewart had both previously recorded it from Belfast.

T. fabula, Gronovius. Bell records it from the Belfast deposit. The writer obtained one perfect example in the estuarine clay of the Bann, and a single valve in the Limavady bed.

*T. squalida, Pulteney. "The only specimens I have seen were single valves collected by the late William Thompson, Esq., and by Mr. Wm. Darragh "-Stewart. Darragh's specimens are in the Belfast Museum. One single valve and a fragment were found in the Belfast bed by Grainger, and recorded in the list supplied to Mac Adam's Paper (as T. depressa), but omitted from Grainger's subsequent Paper on account of a doubt as to the correctness of the determination; but the specimens, which I have examined, show that the record was correct.

Psammobia ferröensis, Chemnitz.

Sparingly but widely distributed in the Belfast clays, having occurred successively to Hyndman, Grainger, Stewart, and the writer. A few valves at Limavady Junction is my only other note of the species.

P. vespertina, Chemnitz. Grainger records a single valve from the Belfast bed; two additional valves were subsequently found there by him, and are preserved in his cabinet. I obtained two valves in the Magheramorne clay.

Mactra solida, Linn. Very rare. Bell records it from the Belfast bed; and the writer obtained one valve at Magheramorne.

*var. truncata was noted by Stewart as rare in the Belfast clay; Bell marks it in his list as found at Magheramorne.