42 THE ESSEX NATURALIST
ments from the Blackwater. The species may be common in the
fine sediments offshore.
Order Acochlidiacea
LIMAPONTIIDAE
Acteonia senestra Quatrefages
Fairly common on mud among the roots of plants in a small
salting above Maldon railway bridge (11.5.1965). May also be
common in other saltings in the area as, being small and green
in colour, it is easily overlooked.
Order Nudibranchia
LIMACIIDAE
Acanthodoris pilosa (Muller)
Always present and sometimes common on clean shelly places
at low tide level and below. Particularly found on stations S.18
and S.19, and in the Thirslet area in 1960 and 1961; also in the
area of Bradwell Creek in 1965. The ribbons of spawn may be
found attached to stones on the lower shore in spring and early
summer.
Ancula cristata (Alder)
Rare in the Blackwater. One specimen was recorded from the
shore at Bradwell in March 1959 and another obtained from the
water intake system of Bradwell Power Station on 2.4.1965.
Dendronotidae
Dendronotus frondosus (Ascanius)
Large numbers of this species were found living in the water
intake culverts of Bradwell Power Station in June 1965, associated
with Tubullaria and actiniarians. There are no previous records
for the area and it can only be assumed that the concrete walls
of the culvert, giving a good habitat for the coelenterates, have
encouraged the establishment of this population.
DOTOIDAE
Doto coronata (Gmelin)
One specimen taken in a trawl haul in the Bench Head area
(22.5.1962). Commonly found on hydroids in Thirslet Creek and
at some points along the north side of the Blackwater during 1964
and 1965.
Facelinidae
Facelina sp.
Numerous specimens were found on shells and among seaweeds
on the lower shore at the entrance to Bradwell Creek and along
the shore towards Weymark's Sluice in May 1964.