A DAY ON THE CROUCH RIVER. 151
slug's back. One brilliant specimen of the bright purple Eolis
coronata, and another dark reddish-brown species of Eolis (either
Eolis concinna, Alder and Hancock, pl. 24, or a new species)
occurred, but these slugs are difficult to preserve, even to make
subsequent identification possible. Doris can be kept well, Doto
fairly well, though it loses its bright colours, but attempts to preserve
Eolis are quite failures. These slugs are handsome and conspicuous
objects when separated from their surroundings, but amongst the
various living Zoophytes and Algae their protective resemblance is
remarkable and they are by no means easily recognised amongst the
varied contents of the dredge or trawl.
Corallines or Zoophytes were, of course, abundant, but we were
neither of us specialists enough to recognise many. Hydractinia
echinata was common on the shells of Purpura lapillus, living and
beautiful; much interest was shown in two specimens we bottled.
The presence of a fine "root" of Tubularia indivisa in a jar, with
its rich bouquet of delicate, but brilliant, white-plumed scarlet flowers,
was also a great surprise to our crew. This Tubularia occurred
many times in the deeper water near the mouth of the river, as did
also a brilliant orange species, almost equally beautiful, but whose
name we did not know. Sertularians were abundant, but all we
recognised with certainty were, Sertularia pumila, S. abietina, S.
filicula, S. argentea, and Hydrallmannia falcata on S. pumila.
Among the Escharidae Cellularia avicularia and Eschara foliacea
appeared to be common.
Of the sponges, several fine pieces of Chalina oculata were
noticed, and both Grantia ciliata and G. compressa occurred,
attached mostly to the larger Sertularians. The "Crumb-of-bread
Sponge" (Halichondria panicea) was not uncommon. Oyster shells,
bored by Clione celata, were seen in thousands.
While we were examining the "rubbish," the crew and the
Messrs. Rogers were busy with the oyster spat, of which several were
found, varying from the size of a pin's head to that of a shirt-button.
Often three or four were found on a shell, thus giving promise of
a good fall of spat; a promise which has been fulfilled, for probably
there was a larger spat in our Essex rivers last year than in any since
1881, but it came late. I heard of as many as forty being counted
on a single shell from the Blackwater this year, varying from the size
of a pin's point to a split pea; sixteen and seventeen on a shell were
not unusual in 1881. This is rather a shock to Mr. Frank Buck-