THE MARINE FAUNA OF THE BLACKWATER ESTUARY 43
Aeolidiidae
Aeolidia papillosa (Linne)
One specimen obtained from wooden posts at Brightlingsea in
1963 and other specimens from Bradwell Creek in 1965. One
dredged from the inshore side of the Barrier Wall in February
1965 was spawning.
Sub-class PULMONATA
Order Basommatophora
Ellobiidae
Leucophytia bidentata (Montagu)
Fairly common among the roots of plants in saltings at the
seaward end of the Blackwater and especially around Mersea
Island. Shells are common in the litter at high water mark in the
saltings.
Phytia myosotis (Draparnaud)
Very common in saltings, living among the roots of plants and
under damp litter, pieces of wood, etc. Extends from the Phrag-
mites marsh above Maldon bridge to the open sea coast, covering
a wide range of temperature and salinity regimes. The variety
denticulata (Montagu) occurs in the Colne. Many specimens
have a line of fine 'hairs' below the suture which may be well
enough developed to give the appearance of a 'keel' as in
Hydrobia jenkinsi.
Class SCAPHOPODA
Dentaliidae
Dentalium sp.
Only two shells, both in poor condition, have been recorded.
One was obtained from fine sand in the Swin Channel (4.6.1965)
and the other from mud on the shore at Bradwell (10.7.1965).
Class LAMELLIBRANCHIATA
Order Protobranchia
Nuculidae
Nucula nucleus (Linne)
Most commonly recorded from bottoms of fine shell and sand
but can tolerate a certain amount of mud in the sediment. Ex-
tends from Osea Island to the Bench Head area. From the
sampling carried out there does not seem to have been the mor-
tality that was observed in other parts of the British Isles during
the severe winter of 1962-63 (Crisp et al., 1964).
Nucula tenuis (Montagu)
The status of this species has not been established but it seems
to be common on sandy bottoms beyond the mouth of the Black-
water and in Whitaker Channel.