GrevillE; on New Diatoms. 
3 
The largest and finest of all the known Cresswelli(B, dis- 
covered by my acute and very obliging correspondent^ Mr. 
J. Linton Palmer, Surgeon, R.N., who has kindly trans- 
mitted many new things, accompanied with notes and 
sketches. One large diatom of singular interest I hope 
shortly to publish as a new genus, under the welh merited 
name of Palmeria. The subject at present under considera- 
tion is a giant in Cresswellia, the frustules being no less than 
•0030'' to -0035'' long, and '00 W broad, somewhat con- 
tracted towards the suture. The connecting processes are 
twenty and upwards, and truncate, as in C. Tun^is and 
turgida, and situated just within the margin of the truncate 
end of the valve. A very remarkable character is conspicu- 
ous in the structure, which, near the suture, is punctate, but, 
by degrees, becomes more and more distinctly cellulate, the cel- 
lules towards the ends being hexagonal, and about ten in -001'^ 
I have as yet seen only two frustules in connection. While 
engaged in preparing this paper, I was agreeably sur- 
prised to discover in some Shark^s Bay slides, in the 
cabinet of my friend, Mr. George Norman, both front and 
side views of this species. For the finest example in 
own cabinet, I am indebted to the generosity of Lawrence 
Hardman. Esq., the well-known diatomist and admirable 
microscopical manipulator, whose friendly assistance in some 
very critical investigation, I shall hereafter have a more 
favorable opportunity of acknowledging. 
Cresswellia cylindracea, n. sp., Grev. — Frustules cylin- 
drical (not contracted at the suture), truncated, unequal in 
length ; connecting processes numerous, fine, truncated ; 
structure obscure. (Fig. 10.) 
Hab. Hong Kong harbour ; May and June ; John Linton 
Palmer, Esq. 
Another very notable species, which we owe to the exertions 
of Mr. Palmer. It exhibits a larger number of frustules in 
connection than any other hitherto observed, and, at first 
sight, bears no inconsiderable resemblance to a Melosira. 
The connecting processes, and even the suture, are incon- 
spicuous in specimens preserved in balsam, but come out 
more distinctly when burnt on the cover and mounted dry. 
The structure is dense and obscure, the colour pale, with a 
tinge of yellow. 
It is by no means rare in one of the gatherings kindly 
sent me by its discoverer. Length of frustules "0015'" to 
•0025"", or more ; breadth about '0018"". 
Cresswellia Barhadensis, n. sp., Grev. — Small; frustules 
elliptic, conspicuously cellulate ; suture sharply prominent ; 
