248
THE ESSEX FIELD CLUB.
MOLLUSCA DREDGED OR TAKEN IN THE BLACKWATER
ESTUARY.
Lamellibranchiata :—
Anemia cphippium, L.
Ostrea edulis, L. (Oyster). Abundant.
Pecten varius, L. (Small Scallop).
Mytilus edulis, L. (Mussel). Abundant.
M. barbatus, L.
Modiolaria marmorata. Forb. Common.
Nucula nucleus, L. Several specimens.
N. nitida, G. B. Sow. Several
specimens.
Cardium echinatum, L. (Spined
Cockle).
C. exiguum, Gm. Common.
C. edule, L. (Common Cockle.) Com-
mon.
Tapes pullastra, Mont. Abundant.
T. virgineus, L. 1 specimen.
T. aureus, Gm. Common.
Tellina balthica, L.
T. tenuis, Da C.
Donax vittatus, Da C.
Mactra solida, L.
M. subtruncata, Da C. Common.
Scrobicularia piperata, Gm. Very
abundant.
Thracia papyracea, Poli.
Mya arenaria, L. (Gaper Shell). Very
common, Osey Island.
M. truncata, L. (Gaper Shell). Com-
mon.
Pholas Candida, L. (Rockborer). Not
common.
Gastropoda :—
Chiton cinereus, L. (Coat-of-mail
shell). Common.
C. fascicularis, L.
Patella vulgata, L.
Trochus cinerarias, L. Abundant.
T. magus, L.
T. umbilicatus, Mont.
Littorina obtusata, L. (Periwinkle).
Common.
L. rudis, Maton. (Periwinkle). Very
common on Osey Island.
L. littorea, L. (Common Periwinkle).
Very common on Osey Island.
Rissoa membranacea, Ad. Common.
Hydrobia ulvae, Penn. Abundant, Osey
Island.
Odostomia lactea, L. (Chemnitzia ele-
gantissima). 3 specimens.
Velutina laevigata, Penn. 2 speci-
mens.
Purpura lapillus, L. Common.
Buccinum undatum, L. (Whelk).
Common.
Murex erinaceus, L.
Nassa reticulata, Lmk. (Dog Whelk).
N. incrassata, Str.
Pleurotoma (Mangelia) rufa, Mont.
Utriculus obtusus, Mont. 1 specimen.
Accra bullata, Mull. Osey Island.
Melampas myosotis, Drap.
Mr. E. M. Holmes reports that "the Blackwater, so far as we explored it,
seems to be remarkably poor in Marine Algae. The list appended includes all
that I was able to find, and these were mostly dredged up. The occurrence of
Fucus nodosus var. scorpioides, J. Ag., has not been previously recorded in Great
Britain, so far as I know. It is a very remarkable form, growing in dense patches
on soft mud on Osey Island, in company with Fucus vesiculosus var. subecostatus,
and a spirally twisted var. of F. vesiculosus. The occurrence of the F. nodosus
var. scorpioides is the more remarkable that not a single specimen of the typical
form of the plant was met with. The frond is not larger than that of Gravilaria
confervoides, and were it not for its yellowish-brown or olive colour, and the
short, opposite, patent ramuli here and there, might easily be mistaken for it.
The fronds, also, are nearly cylindrical, instead of compressed, as in the type of
the species. It was growing in tufts about 3 inches high, and 6 to 9 inches in
circumference."
MARINE ALGAE IN THE BLACKWATER ESTUARY.
MELANOPHYCEAE : —
Fucus vesiculosus, L.
f. spiralis.
f. subecostatus, Harv.
F. ceranoides, L.
Melanophyceae (continued):—
F. nodosus, L.
var. scorpioides, J. Ag.
Laminaria saccharins, Lamour.