APODA. 
423 
transparent circle. On full considerations of the descriptions and figures 
of P.jlexilis , Daly ell, and P. subauriculata, Johnston, I cannot — although 
it is opposing my ignorance to Dr. Johnston’s knowledge of the subject — 
believe the species to be distinct. My specimens agree about equally well 
with both species. Further, it may be remarked that my specimens have 
presented the form of Polycelis pallidus, Quatrefages (Ann. Sci. Nat., t. iv. 
pi. 3, f. 8, 1845), to which they seem nearly allied ; the eyes are just as 
represented in the highly magnified fig. 9 of that species. It was obtained 
by M. Quatrefages on many parts of the coast of Sicily. The P.jlexilis 
was procured in the Firth of Forth, and P. subauriculata in Berwick 
Bay. 
P. stagnalis , Mull. 
North of Ireland, Mr. Templeton. 
P. lactea, Mull. 
This species is marked with doubt from the circumstance of its differ- 
ing in the following characters from P. lactea. The chief central vessel 
represented in the figure as of about equal breadth throughout, expands 
in this into an ovate form about the centre of the body — and the ramifica- 
tions from it, represented as purple in P. lactea, are in this of a rich fawn- 
colour. My specimens are 9 lines in length, when the breadth is 2 lines ; 
eyes pyriform, generally two in number, placed as in P. lactea (a speci- 
men had two at one side, and one eye at the other) ; colour milk-white, 
but the main vessel and its ramifications, spreading throughout all the 
body except the mere margin, imparts a handsome delicate fawn-colour 
to the animal. All of the many specimens taken were of the same colour ; 
the size already noted marks them as considerably larger than Muller’s. 
When in motion they were generally more elongate (of about equal 
breadth throughout) than P. lactea is represented to be, but occasionally 
appeared of the same form as the figure in the Zoologia Danica. 
During an excursion round the shores of Lough Neagh at the begin- 
ning of August, 1846, when I was accompanied by A. H. Haliday, Esq., 
this species was found to be very common, attached to stones at the 
margin of the lake, and to subaquatic plants. It was gregarious, several 
individuals being generally adherent to the under side of a stone a few 
inches in diameter. 
P. nigra, Mull. 
This species was found abundantly in the same localities, and under 
similar circumstances with the last. With the unimportant exception of 
being more of a brown colour and of rather less size, they perfectly 
agreed with the figure in the Zoologia Danica, and also with the descrip- 
tion, so far as given. They were when fully extended 3 lines in length ; 
under a high magnifying power a row of black dots appeared closely dis- 
posed round the margin of the anterior part of the body. Sir John G. 
Dalyell figures similar dots in his P. nigra (Observations on Planariae, 
fig. 5), hut in my specimens there are three for one represented in it — in 
the description however they are mentioned as numerous. 
August 22, 1846. — Three Planarice, agreeing with Sir J. G. Dalyell’s 
P. nigra, and brought from the pond in the Zoological Garden, Phoenix 
Park, Dublin, with Hydrce, &c., in May last, are now living before me. 
These differ from the P. nigra of the Zool. Dan. in being of a jet-black, 
of a much softer consistence, more shapeless, and being able to diminish 
themselves to a much less size. 
