LINDSAY, ON THE PROTOPIHYTA OF ICELAND. 201 
2. N. verrucosum, L. 
Throughout Europe, North America, and New Zealand. 
3. N. lichenoides, Ag. 
Throughout Europe. 
2. Oscillariacee. 
1. Oscillaria ( Oscillatoria of older authors). 
O. tenuis, Ag. Distributed throughout Europe ; occurring 
at Plombiéres, Aix, and Dax, in thermal waters. 
2. Phormidium vulgare, Kiitz., var. myo- 
chroum, Kiitz. 
(Oscillatoria, autumnalis, Ag., of my ‘Flora,’ p. 36.) 
Throughout Europe. 
3. Chthonoblastus repens, Kiitz. 
(Microcoleus, Hary., of my ‘ Flora,’ p. 36.) Throughout 
Europe. 
3. Rivulariacee. 
1. Zonotrichia atra, Lyngb. 
(Rivularia, Roth, of my ‘ Flora,’ p. 36.) Marine; coasts 
throughout Europe. 
2. Gloiotrichia angulosa, Roth. 
(Raphidia Hass., of my ‘Flora, p. 36.) Throughout 
Europe. 
Certain genera of the Nostochacee are widely distributed, 
and are very abundant in the Arctic regions and other parts 
of the world. They frequently give a predominant tint to 
large masses of water; for instance, in lakes in moun- 
tainous countries such as Scotland and Switzerland. 
Some genera or species of the Oscillariacee are cosmopolite.* 
‘They mostly inhabit fresh water, or grow on moist or wet 
shady rocks, such as those about waterfalls or springs, in 
ravines or gorges—in localities, that is, which are also fre- 
quented by Hepatice. 'The commoner forms constitute a slime 
on the rocks or surfaces on which they occur. They are also 
partly marine, the marine forms being the largest. One of 
the marine genera is of very peculiar habit, forming a scum 
on the surface of the sea for many miles. Some species also 
give a peculiar tint to large masses of fresh water, as the 
Nostochacee do ; they are common in hot springs. Sometimes, 
like certain Lichens, they are found on bleaching bones. 
in Europe alone amount to about sixty, to the Lichens. The absence of 
apothecia and spores is, however, a serious obstacle to its ranking as a Lichen- 
genus. 
* The genus Oscillaria occurs in latitude 75° 49’ north. 
