LINDSAY, ON TBE PROTOPHYTA OF ICELAND. 199 
9. Campylodiscus Kiitzingii, Bail. 
10. Eunotia bidens, Ehrb.* Fossil in Oldenburg (Prussia). 
There can be no doubt that this is a terribly inadequate 
representation of the Diatoms of a country, which cannot fail 
to be rich in them. Quite recently, while examining some 
fragments of a Conferva from the hot springs of Laugarness, 
near Reykjavik, Dr. McNab found species of at least six dif- 
ferent genera (viz., Cymbella, Epithemia, Stauroneis, Pinnu- 
laria, Synedra, and Gomphonema);+ and he remarks on their 
identity in many cases with Scottish forms that inhabit cold 
waters. From the same hot spring I brought home, in 1860, 
specimens of Conferve, which I sent to Dr. Greville, and 
which must have abounded more or less in Diatoms; but I 
never heard the result of his examination, if he did examine 
them at all. In Iceland, thermal waters of all degrees of 
temperature abound ; and they are characterised by the large 
amount of silica they hold in solution, and by the extent of their 
siliceous deposits.t The abundance of Diatoms in the thermal 
waters of Central and Southern Europe warrants us in ex- 
pecting large additions to the Icelandic Diatomacez from this 
source alone. But rivers and streams, shallow lakes and 
extensive marshes, also abound—habitats which are generally 
fertile in Diatoms in other parts of Northern Europe, and of 
the world generally. Moreover Diatoms occur in the ejecta 
(dust, ashes, sand) of the voleanoes—extinct or active—of 
Southern Europe and other parts of the world, and these 
ejecta are abundant in Iceland. The Palagonite and other tuffs 
* The list of species here given is cited as Icelandic on the faith of Dr. 
Rabenhorst’s ‘ Flora Europea Algarum Aque Dulcis et Submarine,’ Leipzig, 
1864-5, which comprises the Diatomacee and the Phycochromacee (the latter 
including the Chroococcacee, the equivalent of the Palmellacee of the older 
authors, and the lower Chlorospermous Alga, viz. Oscillariacee, Nostochucea, 
Rivulariacee, Scytonemacee, and Sirosiphonacee). The work is a most 
comprehensive one, exhibiting great labour in compilation, and probably 
representing fairly, as it professes to do, the present state of our knowledge 
of the distribution of these organisms in Europe. It is impossible, how- 
ever, to place implicit confidence in his citations of localities ; for, in regard, 
_ at least, to Scottish species, he has fallen into several important errors. For 
instance, he records Lismore (Carmichael) as in Iceland ; and Braemar, 
Killiecrankie, Cumbrae, and the Frith of Clyde, as in England ! 
+ “ Notice of some Diatomacee from Iceland,” ‘ Proceed. Botan. Society 
of Edin.,’ February 14th, 1867. 
¢ This is shown by the results of analyses of the hot-spring waters and 
deposits brought home by me in 1860, as published in my paper ‘On the 
Eruption in May, 1860, of the Kétlugjé volcano, Iceland,” ‘Edin. New 
Philosophical Journal,’ January, 1861, p. 18. Vide also “Contributions to 
the Natural History of Volcanic Phenomena and Products in Iceland,” 
* Proceed. Royal Society of Ediu.,” December 17th, 1860, vol. iv, p. 387. 
