INTRODUCTION TO CRTPTOGAMIC BOTANY. 143 



could do SO consistently, if Noatoc and Ghoetophora were asso- 

 ciated -with the simpler forms. The species are extremely 

 numerous, though in general obscure; a few, however, are 

 remarkable for their beauty, and none more so than Petalo- 

 nema alatum, in which the investing tube is so broad, and 

 the lines of growth so distinct, that, in conjunction with the 

 beauty of the colouring, the characters seem to point to some- 

 thing much higher in the scale of vegetation. OscillatoricB 

 occur in all parts of the world under some form or other; and 

 though the greater part inhabit fresh water, damp shady spots, 

 or rocks down which water trickles, they, are by no means 

 deficient in the sea, where perhaps they attain their greatest 

 size. Numerous species affect thermal springs, and a very 

 noble kiud, of a deep red, forms thick woolly fleeces in the 

 hotter parts of India, as in the hot valleys of the great Rimjeet, 



Fig. 35. 



ErythroTiema HooJcerianum, Berk. 



Magnified from specimens received from Dr. Hooker, gathered in 

 nullahs, at Fitcoree. 



ascending up to the subalpine regions, which border the Hima- 

 layas. A few grow like Lichens on the trunks of trees, and 



