NoRMANj on Diatomaceee. 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"; diameter of 

 valve -0013" 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. Striae 

 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 Brehissonii, vivax, and bilobata. . <r 



5. Aulacodiscus Sollittianus, 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 



