Norman, on Diatomacece. 
7 
3. Coscinodiscus fuscus, n. sp.. Norm. (Fig. 3). — 
Valve convex, depressed in centre ; granules arranged in 
radiating lines, diminishing in number at intervals, thus 
forming distinct zones. Granules 20 in '001'' j diameter of 
valve -0043" to -0067". 
Marine, stomach of Ascidians, North Sea. 
Valve, under a low power, opaque, brownish black, lighter 
in centre, where it is green. At first sight it reminds one 
of Eupodiscus Ralfsii ; but the colour is much darker, the 
granules much smaller, and more crowded together. In 
this respect it appears to be half way between E. Ralfsii and a 
disc which I found in considerable quantities on bones from 
Constantinople, and which has been doubtfully referred to 
Eupodiscus subtilis. 
The want of anything like a marginal nodule in the species 
now described, relieves me of any uncertainty as to its 
proper generic position ; hence I refer it, without hesitation, 
to Coscinodiscus. Hitherto it has occurred only in one or 
two ascidian gatherings, and then only sparsely. 
4. Nitzschia vitrea, n. sp.. Norm. (Fig. 4). — Frus- 
tule hyaline, broadly-linear, extremities truncated ; valve 
linear-lanceolate, slightly constricted in centre, and somewhat 
produced at the ends ; puncta conspicuous, bead-like. Strise 
very obscure, 58 in -001". Length of frustule "0025'' to 
•0055". 
In brackish water, Hull. 
'It is not often that one has the good fortune to detect a 
new British form. The present one, however, cannot be 
referred to any of the species given in Smithes ^ Synopsis.^ 
The only locality that has hitherto yielded it is a small ditch 
of water influenced by high spring tides. The same locality 
furnishes Nitzschia Brebissonii, vivax, and bilobata. 
5. Aulacodiscus SoUittianus, n. sp.. Norm. (Fig. 6). 
— Disc large, colourless, processes very prominent (about 
six), submarginal. Granules in radiating lines, 9 in -001", 
absent in centre valve and around base of processes. 
In a deposit from Nottingham, Maryland. 
Diameter of valve '009" ; processes large, and, under a 
low power, appearing as if they had rings attached to 
them. 
This fine species I have great pleasure in dedicating to 
Mr. J. D. Sollitt, whose long services with the microscope, 
conjointly with Mr. Robert Harrison, have, I think, been 
insufficiently recognised. 
Unfortunately it is very scarce in the small quantity of the 
deposit I have hitherto worked upon. I expect soon to have a 
