48
THE ESSEX NATURALIST
Mactridae
Mactra Corallina cinerea Montagu
Shells occasionally found on beaches at the mouth of the
Blackwater. Shells, in good condition, were obtained from Buxey
Sand and by dredging in Swire Hole (1962). No living specimens
have been found.
Spisula elliptica (Brown)
Shells and living specimens have been obtained from a variety
of bottoms at the seaward end of the Blackwater and from the
Colne Bar area in May 1965. Shells are commonly found on most
shores.
Spisula subtruncata (da Costa)
Shells have been found on the shores and in the bottom sedi-
ments of the Blackwater. Some living specimens were dredged in
Whitaker Channel in June 1965.
Myidae
Mya truncata Linne
Shells common on the shores. Living animals taken less fre-
quently, mostly from bottom samples of mud, shell and gravel
in the Thirslet area (1960 and 1961).
Mya arenaria Linne
Very common in sandy mud and mud on the lower shores, in
creeks; juveniles occasionally below low water mark. Shells
commonly occur on all beaches.
Sphenia binghami Turton
Small specimens sometimes taken alive; mostly on the cleaner
bottoms. HB3 (18.8.1960), S.19 (21.9.1960), C.3 (7.2.1962), and
Eagle (25.5.1962).
Erodonidae
Corbula gibba (Olivi)
Only one record; a living, adult specimen, dredged from a
bottom of sand and shell south of Bachelor's Spit (7.1962).
Hiatellidae
Hiatella arctica (Linne)
Shells common on the shore. Living specimens found burrow-
ing into soft stone or attached by byssus to dead mollusc shells
and Sabellaria colonies. Also found among fouling in the water
intake culverts of Bradwell Power Station. Generally distributed
in the Blackwater and offshore. There is some variation in the
forms of the specimens collected but all have been grouped as
H. arctica.