INTRODUCTION. XXV11 



wide and comprehensive plan, and given to the world, in his late 

 great work, the ' Microgeologie,' the results of researches to 

 which he has devoted an amazing amount of laborious patience. 

 Many of the gatherings described by this writer belong to for- 

 mations of a date sufficiently recent to illustrate the distribution 

 of living forms, but unhappily the want of specific descriptions, 

 and of minute accuracy in the figures, are serious drawbacks to 

 the value of the ' Microgeologie ' in* the hands of other ob- 

 servers not in possession of the specimens themselves, and leave 

 much to be desired by those who would seek to adopt its state- 

 ments as the basis of their generalizations. Without the con- 

 firmatory evidence of personal observation, I therefore hesitate 

 to bring my own experience into parallelism with the statements 

 of this great authority, and content myself with the humbler 

 task of mentioning a few casual facts that have fallen under my 

 own notice ; many of them will be found recorded in the body 

 of this work ; but a notice here of some of the more curious or 

 important may interest the general reader. 



Of freshwater species frequent in the British Islands, the 

 following seem almost cosmopolitan, viz. Si/ncdra radians, Pin- 

 nularia viridis, Pinnularia borealis, and Cocconema lanceolatum. 

 Gatherings from many localities in Europe, from Smyrna, and 

 Ceylon, from the Sandwich Islands, New Zealand, and New 

 York, from the loftiest accessible points of the Himalaya in Asia, 

 and the Andes in America, have supplied specimens of these 

 forms. 



Navicula serians abounds in all our mountain bogs, and is 

 equally common in the marshes of Lapland and America. 



JEpithemia gibba is an inhabitant of the Geysers of Iceland 

 and the lakes of Switzerland. 



The South Sea Islands supply Stauroneis acuta, and Ceylon 

 Synedra Vina ; while Stauroneis Phcenicenteron is equally abun- 

 dant in Britain, Sicily, and Nova Scotia. 



These notes of localities will give some idea of the wide 

 distribution of our fluviatile Diatom acese ; more numerous 

 gatherings would no doubt greatly extend the list, and the 

 following circumstance will show how generally our commoner 

 British forms are diffused throughout European localities that 



