78 
GeevillEj on New Diatoms, 
Hah. North Sea^ off the coast of Yorkshire^ in the sto- 
machs of Ascidians ; George Normanj.Esq. Hongkoug ; J. 
Linton Palmer, Esq. 
The diatom above indicated by my friend Mr. Norman I 
find, on examination, to be identical wilh the specimens 
kindly communicated to me by Mr. Palmer from Hongkong, 
where it appears to be abundant. The remarkable longitu- 
dinal costse, seven or eight of which are sometimes visible at 
once, constitute an admirable character. Under a high power 
the costse are seen to be dilated at their apices, and attached to 
those of the adjoining frustule. 
Cresswellia. 
Cressioellia 7'udis, n. sp., Grev. — Valves convex, depressed 
at the apex, minutely cellulate, with a circle of numerous, 
short, obtuse spines towards the margin, and a row of similar 
smaller ones round the depressed apex. Diameter, -0035" 
to -0040". (Fig. 7.) 
Hab. Monterey deposit ; L. Hardman, Esq. ; R. K. G. 
Distinguished chiefly by the numerous, short, clumsy 
spines, which are nearly of the same thickness from their 
base to their apex, which is often encumbered with fragments 
apparently torn from the spines of the valve to which they 
have been attached. The outer circle is situated at some dis- 
tance from the margin ; then come a few very small, scattered 
spines, which are probably sometimes wholly absent; lastly, 
the inner circle crowning the flattened apex. The substance 
is somewhat thick, and the cellules nine in '001^^ Neither 
Mr. Hardman nor myself have been so fortunate as to find 
entire frustules; but this is of little consequence, as the 
valves in this genus are simply repetitions of each other. 
COSCINODISCUS. 
Coscinodiscus LewisianuSj n. sp., Grev. — Disc oval or ob- 
long; granules conspicuous, forming an irregular central 
cluster, from which a few nearly straight, wide lines radi- 
ate to each end, and some very short ones to each side ; 
margin striated, with an interior narrow band of minute 
puncta. Length, -0024^' to -0045^^ (Figs. 8—10.) 
Hab. Rappahannock deposit. United States ; E. W. Dallas, 
Esq. ; R. K. G. 
I have not been able to find any description of this well- 
marked and beautiful species. The form renders it at once 
