ON THE RECENT OCCURRENCE OF AN HALACARID. 61
Last year Mr. Scourfield found the same mite in fresh water
in the Isle of Man, and now this year he has found it in a pond
in Epping Forest. There is no doubt of its being the same mite
as Mr. Macer's. In the Epping Forest specimen the median eye,
as in the Weybridge specimen, is very pronounced, and I can
also get a very faint indication of the four dorsal plates shown
in the drawing by Hodge, but I am quite unable to see the lines
shown in the cuticle between the plates. This may be that
all the specimens I have seen have not quite reached the adult
stage.
Trouessartella falcata (Hodge) is the type species of the
genus. It was found by Hodge in Seaham Harbour. Two
specimens were found in washing zoophytes from 20 to 30
fathoms depth. Hodge says his specimens were orange brown
in colour. The Epping Forest specimen was a dirty yellow.
The description given by Hodge agrees in all particulars with
the Forest example. As regards the dorsal surface, Hodge says
"upper surface of shield divided by delicately sulcated lines
into four regions,' the interspaces being free from markings ;
the anterior and two lateral spaces may be said to represent
the thorax, and contain the eyes, whilst the posterior may
naturally represent the abdominal portion of the animal. An
irregular dark line extends from the median eye to opposite the
insertion of the last pair of legs." Length of body to tip of
rostrum 0.80 mm., body only to back of rostrum bulb 0.50 mm.
Previously recorded from both salt and fresh water.
There is another mite mentioned by Lohmann in Das Tierreich
as recorded from fresh water only in England, namely, Rhombo-
gnathus nigrescens Brady. I have examined Brady's figure,
but it is quite a different mite from the one found in Epping
Forest.
Palaemonetes Varians at West Ham.—Living specimens of the
"freshwater prawn" were recently (Sept., 1924) brought for identification
to the Stratford Museum, which had been taken from a ditch on the river-
marshes near Prince Regent Lane, West Ham, associated with Gammarus
and other fresh-water organisms. The occurrence of this prawn within
the metropolitan area of the County is interesting. The ditch in which
it was found has probably occasional connection, by means of sluices,
with the Thames at Beckton.—Percy Thompson.