inhabiting the Estuary of the Dee. 197 
pany with EZ. concinna and E. despecta: this is E. exigua, which 
inhabits the same fronds of Laomedea gelatinosa as the other 
two, being found in rock-pools considerably above low-water 
mark; but it appears to be much less numerous than E. de- 
specta. There are thus four species existing in the Mersey 
which have not hitherto been met with in the Dee; and it will 
presently appear that the Dee possesses five species which have 
not yet made their appearance in the Mersey. The Polycera 
Lessonii, recorded as dredged off the Mersey, was taken about 
midway between the two estuaries, and can hardly be claimed, 
therefore, as the especial property of either. 
Among those species common to both estuaries, one, however, 
deserves especial mention, viz. Doris proxima, from the fact that 
although found both in the Mersey and Dee, I am not aware of 
its having been taken anywhere else. In external characters it 
closely resembles D. aspera; but it is not a little remarkable 
that D. aspera has not yet been detected on these shores. I 
have searched in vain for it myself, nor can I hear that any one 
else has taken it*. It appears to be replaced by its ally D. 
prozima. This fact would lead one to suppose it to be a mere 
local variety, were it not that the tongue differs so widely in the 
two species that Mr. Alder remarks, “some naturalists might be 
disposed to consider them generically distinct.” 
I had the satisfaction of adding to the local list, in the autumn 
of 1859, Eolis rufibranchialis, characterized as one of the most 
slender and delicate forms of the genus. This beautiful species 
I first met with in July, at Hilbre Island, in the Dee, where it 
was of large size, and in some numbers. Visiting the Egremont 
shore of the Mersey in March of the present year, I was sur- 
prised to find as many as two dozen specimens of this brilliant 
creature where I had never seen it before. They were very 
brightly coloured, but not so large as the examples taken in 
the Dee. 
The hunting-ground for these little animals in the estuary of 
the Dee is of very limited extent. On the Cheshire side, long 
before the time of low water, the tide runs out, leaving a vast 
and bare expanse of sand, most unproductive of animal life. 
The river is six miles wide at its mouth; and with the Welsh 
side Iam unacquainted, owing to its distance and inaccessibility. 
But about a mile and a half from Hoylake, at the north-west 
angle of the Cheshire shore, commences a ridge of New Red 
Sandstone, nearly parallel with the coast, extending up the river 
* In a note now before me, from Mr. Price, he says, “ Every Doris 
(aspera) I ever suspected and sent to Mr. Alder, he pronounced to be D. 
proxima. They were sometimes pure white; their spawn dull yellow and 
inconspicuous, forming a squarish spiral.” 
