The Terrestrial Mollusca of the Great Blasket and Beginish

The Terrestrial Mollusca of the Great Blasket and BeginishAuthor(s): A. W. StelfoxSource: The Irish Naturalist, Vol. 21, No. 10 (Oct., 1912), pp. 185-190Published by: Irish Naturalists' Journal Ltd.Stable URL: http://www.jstor.org/stable/25523993 .

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Irish Naturalist, Vol. XXI. Plate 3j

lH?iijllBBiB

Fig. 1?Looking S.W., showing Foilbeg and Slievedonagh

(937 it.) Tearaght in distance.

A. W. Stelfox, Photo.

Fig. 2?Looking N.E., showing Croaghmore (961 ft.).

North Coast of the Great Blasket.

Tc face b^ 185.



October, 1912. The Irish Naturalist. 185

THE TERRESTRIAL MOLLUSCA OF THE GREAT BLASKET AND BEGINISH.

BY A. W. STELFOX.

(Plate 3.)

It is not difficult to imagine a time when the Blaskets

formed a portion of the mainland of Kerry. Only two of

the islands?The Tearaght and Inishtooskert?lie without

the twenty-five fathom line. Numerous small islets or

illauns, and reefs exist between the Great Blasket and the

coast of the Dingle peninsula opposite. Many of these

smaller islets, as well as Beginish, are capped by Glacial

drift and it is apparent that the sea is rapidly wearing them

away. Even on the Great Blasket considerable wastage appears to be going on, except at the eastern end of the island

where blown sand is accumulating. The fauna of the

islands will naturally, therefore, be closely related to that

of the nearest part of the mainland, unless we are to believe that these western islands are stocked by specimens carried

by chance means from all points of the compass. Four days were spent by me on the Great Blasket, in

company with Mr. & Mrs, R. Lloyd Praeger in June, 1912, and about two hours on Beginish. Before reaching the

islands I made a rough list of species which I expected to

find there. In making this I was guided mainly by the

lists which have been compiled on the western islands of

Galway, Mayo, and Donegal, and that from the adjoining mainland of Kerry, since no information concerning the

mollusca of the Blaskets has been published hitherto. This

provisional list contained thirty-six species, two of which were fresh-water species. Of these all but nine were found on the Great Blasket, while five species which I had not

counted upon procuring?though none of them caused any

great surprise when found?turned up also.

The nine species looked for and which I could not find

were Agriolimax laevis, Arion circumscripta, Zonitoides

excavatus, Punctum pygmaeum, Hygromia hispida/ Vertigo

pygmaea, V. antivertigo, Acicula lineata and Pisidium

personatum. Oi these Z. excavatus appears to be absent

from the extreme west of the Dingle promontory. H. hispida



l86 The Irish Naturalist October,

appears to be absent, though no reason for this can be

given; but as no really natural habitat for fresh-water

species occurs on the island during dry weather P. personatum could not be expected to find a dwelling-place. The

remaining six species should occur, and it is just possible that the dry summer of 1911 and the drought during April and May, 1912, may have caused a temporary shortage, and

hence a second visit to the island might reveal their presence. The five unexpected species found were Limax maximus,

L. cinereo-niger, Sphyradium edentulum, Helicella virgata and

H. intersecta. All of these occur on the opposite mainland.

Since Mr. Praeger has described already (pp. 157-158

supra), the main features of the Great Blasket I need not

repeat these. The chief points from a conchologist's point of view are, however, as follows :?

(a) A quick run-off of rain and hence want of standing water.

(b) The crumbling nature of the north-western cliffs, well shown in the two photographs on plate 3, and therefore scanty vegetation and little shelter for mollusca.

(c) The destruction of the vegetation by grazing sheep over the greater portion of the island; and

also by wind and sea along the western and

south-western slopes, which are very dry and

bare.

(d) The influence of man appears nil, and no species seems to have been artificially introduced.

LIST OF SPECIES FROM GREAT BLASKET.

Limax maximus L.?A single very large specimen, slightly paler than

the type in colour, was taken at dusk just emerging from its retreat

beneath one of the thousands of rock-slabs scattered over the slopes between Garraun Point and Canknock, near the north-eastern corner

of the island, at an altitude of about 250 feet. This specimen is the

first example of L. maximus which I have taken on any of the western

islands in an undoubtedly native habitat, all others having been

observed within the precincts of habitations. I cannot agree with Dr. Scharff1 that we must look upon a specimen as a native unless

1 See note on Testacella haliotidea, supra, p. 15,5.



i9r2> S$Ki,FOX.-~ Terrestrial Mollusca of the Blaskets, 187

there is good evidence to the contrary ; it seems to me safer to regard with suspicion?as most botanists do?any specimen which cannot

honestly be considered native.

L. cinereo-niger Wolf.?One line specimen under a stone in the dry bed

of the small rivulet, which in wet weather flows into the gully a quarter of a mile east of Bannig, on the south coast, and a half

grown example under a stone above Coosnacrissaun on the north slope of the island. Both examples were of a pale yellowish-brown ground

colour, with darker spots. A very beautiful variety.

h. arborum Bouch. -Chant.?In extraordinary abundance along the

rocky slopes of the southern coast at night and evidently feeding on . the lichens which cover the surface of the rocks. It is to be met with

also on the greater portion of the island from close to sea-level to the

summit, 961 feet. The prevailing form seems referable to var.

alpesiris Less, and Poll.

Agriolimax agrestis. (L.)?Not seen in the drier parts of the west end, but elsewhere common from sea -level to summit. Mainly typical in colour, and the brownish form which prevails on the islands of Mayo

and Donegal appeared rare.

Milax gagates (Drap.)-?Very common along the north-western cliffs

opposite Illaunbaun and above Coosnarinnisha, but not seen in any other part of the island. All specimens were referable to var. plumbea and rather small in size.

Vitrina pellucida (Miill.)?A single dead shell was taken under a stone

beside the ruined Signal Tower at 765 feet altitude. No doubt

common in winter and spring.

Hyalinia cellaria (Miill.)?On the more northern islands and along the

coast .of western Ireland this species has always proved, so far

as my experience has gone, to be an absentee from the cliffs, and

confined to the cultivated areas, and thus its standing as a native in

those districts has always appeared doubtful. On the Great Blasket,

however, its large form ( Vitrea hibernica Kennard) is abundant on

many parts of the cliffs, particularly near Coosnacrissaun, and at

about 800 feet altitude on the northern escarpment of Slievedonagh.

Here, in fact, this shell takes the place usually filled by H. alliaria

on the western islands, as the characteristic species of the genus. On

the opposite mainland of Kerry H. cellaria lives on the northern

cliffs of Brandon to a height of at least 1,250 feet, its highest recorded

station in Ireland.

H. alliaria (Miller).?Occurs sparingly over the greater part of the island

almost to the most western point. Mainly typical.

H. nitidula (Drap.)?The usual western form with drooping and expanded

body-whorl occurred in several places on the cliffs ; but it was

common only in one place at Foilbeg. Several white specimens were

noted, while most were pale in colour.

H. pura (Alder).?On the northern cliffs : frequent. Mainly 01 ukj

typical form.

42



r88 The bhh Naturalist October,

Hyalinia radiatula (Alder. )--Sparingly round the north-western corner of

the island ; but not seen elsewhere.

H, crystallina (Miill.)?-Rare and only seen occasionally. A small form.

Euconulus fulvus (Mull.)?Several large dead shells at Foilbeg. Evidently not a common species on the island.

Arion ater (L.)-?Frequent bur. not often abundant. Vars. castanea,

plumbea and atexrima were noted.

A, subfuscus (Drap.)?Very scarce and only seen near the village and

along the north-eastern cliffs.

A. intermedins Normand.?Many examples of the bright yellow form

on the damper parts of the cliffs. The grey form was noted also.

Sphyradium edentulum (Drap.)?Near the site of the ruined beehive

huts above Poulabauser,. and at Foilbeg.

Pyramidula rotundata(Mtill.)?With the possible exception of Pupa cylin dracea this must be looked upon as the dominant species over the

greater part of the island. Many colonies of the whitish-green form

were observed, while most specimens were pale in colour.

Helicella virgata (Da Costa).?Abundant at Trabane. Var. submaritima*

common ; var. albina common ; typical form rare.

H. itala (L.)?Common on the sandy cliffs at Trabane.

H. intersecta (Poiret).?Common in the deposits at Trabane, but rare

alive. Also lives on the dry slopes above Coosnafinnisha with V*

pulchella.

H, barbara (L.)?Abundant in the sandy fields and on the slopes at the

western end of Trabane.

Vallonia pulchella (Mull.)?On the dry grassy slopes above Coosnafinnisha

at the north-western corner of the island.

Helix aspersa (Mull.)?Abundant at Trabane and in the fields near by. H. nemoralis (Miill.)?Occurs over the greater part of the island below

300 feet, and common in many of the gullies along the north coast

and at Trabane. This was one of the few species seen in the arid

wastes towards the west end of the island. A large race occurs in

the sheltered parts of the great gully of Foilbeg and also in the deposits at Trabane.

The following forms were taken on the island ;?

auraniia 12345. libellula 12345.

(123) (45) (123)45. 1 (23) (45). 1 (23) (45) (12)345. 1 (23) (45). (12345). (123) (45). 00300. 12045. ooboo. 00300.

castanea 12345. 00000.

(12345).

00300.

00000,

One specimen^of the var. albolabiata was taken at Foilbeg ; the remain

ing specimens all had black or purple lips. None of the castanea form were taken except on the sand at Trabane, where specimens with a band



to*2- STKtFox.? Terrestrial Mollusca of the Blaskets. 189

formula of 00300?the third band often being abnormally broad and

sometimes split?were common.

Some specimens taken on the dry slopes of the island did not measure

more than 17.5 mm. in diameter. These contrasted strongly with the

large race found at Foilbeg, some of which reached a diameter of 24 or

25 mm.

Cochlicopa Iubrica (Mull.)?Not common, but generally distributed.

Pupa anglica (F6r.)?Typical examples were found to be common in

the northern and eastern gullies. Var. pallida occurred frequently, while var. alba was taken at Foilbeg and with V. substriata.

P. cylindracea (Da Costa).?Everywhere, even to the western extremity and to the summit of the Fatal Cliff (over 900 feet). Most examples were referable to the var. anconostoma Lowe. (See Proceedings R. I.

Acad., vol. xxxi., part 23, pi. ii., figs. 47, 48 & 49.)

Vertigo substriata (Jeff,)?A single specimen was taken in damp moss at

about 800 feet on the northern escarpment of Slievedonagh. Clausilia bidentata (Strom).?Frequent in the damper parts of the cliffs.

Carychium minimum (Mull.)?Common in similar situations to the last

species. Limnaea truncatula (Mull.)?This, the sole representative of the fresh

water molluscs, occurred in countless hundreds in one spot at Foilbeg where sheets of the alga Cladophora crispata1 grew over wet rocks.

Above the spot where L. truncatula was found, are several

artificially constructed pools, but no fresh-water shells were

seen in these. In wet weather, rain-pools must form

likewise on the flat peaty ground between the Signal Tower

and Slievedonagh, but I was unable to find any shells here

either.

All the species in the foregoing list are to be met with on

the opposite mainland of Kerry, the Dingle peninsula, and

all are generally distributed throughout Ireland, with the

exception of H. virgata, which is absent from the north

western quarter comprising the county divisions of East

and West Mayo, Sligo, Leitrim, Fermanagh, East and West

Donegal, Derry and Tyrone. On the sandy cliffs at Trabane are various deposits

containing land-shells. None of these, however, appear to

be of great age, though in several cases they are from four

to five feet in depth. The following shells were taken in

these deposits :?Hyalinia cellaria, Helicella itala, H.

intersecta, H. Barbara, Helix aspersa, H. nemoralis, Cochli

copa lubrica and Pupa cylindracea.

1 Named by Mr. Wm. West.



x?0 The hish Naturalist Octobet,

LIST OF SPECIES FROM BEGINISH.

Agriolimax agrestis (L.)?Type and var. lilacina.

Milax gagates (Drap.)?Very common along the northern and western

coasts.

Vitrina pellucida (Mull.)?One dead shell on northern cliffs.

Hyalinia alliaria (Miller)?Type common along northern cliffs.

Arion ater (L.)?Rare. A. subfuscus (Drap.)?Very rare.

A. intermedins (Normand).?Common on northern coast.

Pyramidula rotundata (Mull.)?Common. Helieella inters3cta (Poiret).?On sandy western cliffs.

Vallonia pulehella (MiiU.)?With last species. Helix aspersa (Miill.)?In abundance round the ruins of the old house

Possibly introduced by man.

Pupa cylindracea (Da Costa).?Common. Clausilia bidentata (Strom.)?Rare except in one spot on the northern

cliffs.

Unlike the Great Blasket, this islet is flat, and covered with glacial drift. The run-off is not quick and there

fore the vegetation is rather more luxuriant, in spite of

the grazing of sheep and cattle. There is a large drinking -

pool?which was quite dry, however, on the occasion of our visit?as well as several rain-pools, but no trace of

fresh-water shells was seen on the island.

Belfast.

CERIANTHUS LLOYDII AND ADAMSIA PALLIATA ON THE DUBLIN COAST.

BY NATHANIEL COLGAN, M.R.I.A.

A dredging made in 16 fathoms off Church Island, Skerries, on the 13th July last, yielded me, along with some interesting

Holothurians and Nudibranchs, a single specimen of each

of the above-named Sea-Anemones. So far as I can dis

cover the Ceriantims is an addition to the Dublin marine

fauna, and to the marine fauna of East Ireland, while the

Adamsia, though not new to Dublin, is certainly rare in

its inshore waters. When first detected at the bottom of

a heavy mass of dredged material the Cerianthus had the



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The Terrestrial Mollusca of the Great Blasket and Beginish