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No. 1453.

MARINE LIFE IN THE ST. LAWRENCE.
BY DR. W. BELL DAWSON.



The occurrence of sea shells and other marine creatures on the shores of the Lower St. Lawrence is well known to those who frequent the seaside resorts there ; and the marine forms here referred to have been observed by the present writer who has spent more than one summer at each of the places which are here referred to.
The mouth of the St. Lawence River is placed at Point des Monts, where the estuary narrows appreciably before opening out into the arm of the Gulf of St. Lawrence in which Anticosti is situated. This position for the mouth is recognized in the British Tide Tables as well as by the decision of the Commissioners appointed under the Reciprocity Treaty of 1854. The localities here referred to, can therefore best be described by their distance above this point.
On the south shore, at Metis Beach and Cacouna, resorts that are 53 and 138 miles respectively within Point des Monts, the boulders and rocks of the foreshore between high and low tide, have quantities of periwinkles upon them (the Littorina rudis), and mussels are common near low water (the Mitylus edulis). The whelk (Buccinum undatum) and the Natica are also commonly found, washed up from the deeper water.
On the north shore, at Tadoussac at the mouth of the Saguenay 135 miles above Point des Monts) besides the common mussel there are beds of sea-urchins (Echinus drobachiensis) to be found at the lowest tides, as well as star-fish (Uraster vulgaris). At Murray Bay (172 miles above Point des Monts and only 80 miles below Quebec) the periwinkle abounds as well as the limpet; and star-fish are also found.
At most of these places the clam (Mya arenaria) and the cockle (Cardium lslandicum) are found where conditions are suitable for them.
In the deep water as far up as Murray Bay, sea shells and other marine forms were obtained by dredging, which Sir William Dawson carried out there. The results are described by Dr. J. F. Whiteaves, Naturalist of the Geological Survey of Canada, who himself carried out dredging operations in the Anticosti region. The following quotation is from a Paper by Dr. Whiteaves entitled : On some Results obtained by Dredging in Gaspé and off Murray Bay :—

“ By dredging in the St. Lawrence opposite Murray Bay, 60 species of marine mollusca, identical with well-known Labrador shells, were obtained

p. 3894

by Principal Dawson. It was not previously known that such strictly marine species lived so far up the river. Among the most interesting of these shells is an Astarte. Not only, too, are these Murray Bay shells of a very marine type, but in many cases they are of an unusually large size.” (From Canadian Naturalist, Second Series, Vol. IV, 1869, pages 270-273.)
In another Paper by Dr. Whiteaves entitled : Notes on a Deep-sea Dredging Expedition . . . in the Gulf of St. Lawrence, he thus again refers to the matter :—
“ In the centre of this river (the St. Lawrence) opposite Murray Bay, about 80 miles below Quebec, Principal Dawson has dredged quite a large series of Labrador marine invertebrates ; but how much further up the stream these salt-water denizens extend, we have yet to learn.” (From Canadian Naturalist, Second Series, Vol. VII, 1875; pages 98-99.)
The matter is explained by Sir William Dawson himself in an extended paper entitled : The Post Pliocene Geology of Canada ; published in the Canadian Naturalist, Second Series, Vol. VI. One section of this paper, from pages 369 to 403, is occupied by a list of the mollusca found fossil in the geological deposits, and those still living in the St. Lawrence River and Gulf. From this extensive list, the shells found living in the waters off Murray Bay, have been compiled by the present writer ; and they include the following :—

BRACHIOPODA
(BIVALVE  SHELLS, similar in appearance to the mussel.)
RHYNCONELLA  PSITTACEA.   In great abundance at Murray Bay, in about 20 fathoms.
TERREBRATELLA  SPITZBERGENSIS.   At Murray Bay this is not uncommon, and is found attached to stones in 20 to 25 fathoms.

LAMELLIBRANCHIATA.
(Ordinary bivalve shells.)
KENNERLIA GLACIALIS.     Found off Murray Bay.
LYONSIA ARENOSA.                     ,,             ,,
MACOMA GROELANDICA.            ,,             ,,
MACOMA INFLATA.                      ,,             ,,
ASTARTE LAURENTIANA.             ,,             ,,
ASTARTE ELLIPTICA.                    ,,             ,,
MODISLARIA CORRUGATA.           ,,             ,,
NUCULA EXPANSA.                      ,,             ,,
LEDA MINUTA.                             ,,             ,,

GASTEROPODA.
(Univalve spiral shells, similar to the snail.)
AMICULA EMERSONII.        Found off Murray Bay.
TURRITELLA ACICULA.                ,,             ,,
BELA   ;  (five species.)                 ,,             ,,
BUCCINUM   ;   (six species.)         ,,             ,,
TRICHOTROPIS BOREALIS.           ,,             ,,
CHRYSODOMUS SPITZBERGENSIS. ,,             ,,
TROPHON SCALARIFORME.           ,,             ,,

11 Sept., 1926.

[1927lab]


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