26 
Stodder^ on Diaiomacea*. 
to the Saiidwicli Islaiids and to the Meditemmeaii ; some 
species are found in the Sandwich Islands and the coasts_, 
England^ France, Nova Scotia_, and Botany Bay ; some com- 
mon to Sandwich Islands, Zanzibar, and Florida. 
Diatoms have been long known as the most cosmopolitan 
of all organism. The information afforded by these slides 
adds very much to our former knowledge of this character. 
They seem to exist as species, almost independent of 
climate or locality. 
Mr. Edwards has undertaken to make a list of the Sand- 
wich Island forms, and to figure and describe the new species, 
with the view to publication by our society. I have ex- 
amined tbese slides, prepared by Mr. Samuels, and have 
registered, with Bailey^s indicator,^^ some of the new species 
of Mr. Edwards, as he has communicated them to me verbally 
or by letter, with his provisional names. 
These slides have not been seen by Mr. Edwards, and I 
only am responsible for any errors or mistakes. 
Mr. Edwards's new species are — 
Synedra magna. 
„ pacifica. 
Triceratium circiilare. 
elegans, with 3 and 4 sides. 
imdaturrij with 3, 4, and 5 sides. 
These variations in the number of sides revive the question 
whether there is any generic distinction bet\ycen Trice- 
7'atium and Amphitetras. Mr. Brightwell has described 
several species of four-sided Triceratium, and the only dis- 
tinction I can make out between T. Wilksii and Amp. 
Wilksii of Har. et Bai. (' Proc. Phil. Soc.^) is the number of 
sides. 
Among the rare or recently described forme in the Sandwich 
Islands, are T. dubium (Brightwell), found also on the coast 
of Florida, Cocconeis fimbriata (Brightwell), Biddulphia 
reticidata (Roper). The Campy lodiscus figured by Brightwell, 
in ^ Jour. Mic. Soc.,' as 0. striatus (Ehrenberg), is abundant, 
but bears but little resemblance to Ehrenberg's description 
or original figure. I propose to call it C. Brightwellii. 
Synedra undulata, Greg. (= Towarium undulans, Bail.), is 
abundant, also, at Quincy, Mass. ; so is S. Hennedyana, Grey. 
The two specimens have an expansion in the middle, but one 
is straight, the other undulated ; now, w^e have likev/ise two 
forms, rather rare, one straight, the other undulating, but 
without the expansion: are all four one species? Naviculce 
of the type of N. didyma arc plentiful ; some appear identical 
with described species, but they are so variable that they 
