26 StoddeRj on Diatomacecp. 



to the Sandwicli Islands and to the Mediterranean ; 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 ncAv species, 

 Avith the view to publication by our society, I have ex- 

 amined these slides, prepared by Mr. Samuels, and have 

 registered, Avith " 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 Islv. Edwards, and I 

 only am responsible for any errors or mistakes. 



Mr. Edwards's new species are — 

 Synedra magna. 

 ,, pacifica. 

 Triceratium circulare. 



„ elegans, with 3 and 4 sides. 



„ undatum, with 3, 4, and 5 sides. 



These variations in the number of sides revive the question 

 whether there is any generic distinction between Trice- 

 ratium and Amjjhitetras. Mr. Brightwell Ik-s described 

 several species of four-sided Triceratium, and the only dis- 

 tinction I can make out bet^Aeen T. Wilksii and Amp. 

 Wilksii of Har. et Bai. (' Proc. Phil. Soc.^) is the number of 

 sides. 



Amono- the rare or recently described forms in the Sandwich 

 Islands, are T. dubium (BrightAvell), found also on the coast 

 of Florida, Cocconeis fimbriata (Brightwell), Biddidphia 

 reticidata (Roper). The Campylodiscus figured by Brightwell, 

 in ' Jour. Mic. Soc.,' as C. 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. (= Toxarium undidans, 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, we haA'e likevdse two 

 forms, rather rare, one straight, the other undulating, but 

 without the expansion: are all four one species? Navicida 

 of the type of iV. didyma aiv pliutiiui; some appear identical 

 with described species, but they are so variable that they 



