CRYPTOGAMIA ALGJE. 859 



if it had been finged or Icorched by fire ; the 

 grey colour of the bliO.ers being derived fro:Ti 

 innumerable minute Iioary grains, w\:h which. 

 they are covered, and which give them 2 kind 

 of chagreen afperity. The margin of the leaf 

 in particular, and a corifiderahle portion of the 

 more interior part of it, is covered with a black 

 footy furfuraceous fubftancc, which, by the aid 

 of a microfcope, appears to conlift of numerous 

 branched pedicles, growing in clufters, fome- 

 what fimilar to thofe already defcribed on the L* 

 ^IcmuIiferS!, but much (horter and fmaller, and 

 of a footy colour. No other fru61ifications have 

 ever yet been difcovcred. 



The under fide of the leaf is of a duiky grey or 

 blackilh (;oiour, fmoorh, and without radicles, 

 but full of pits or cavities, correfponding to the 

 blifters on the upper iidc. The only root by 

 which the plant adheres to the rocks is placed in 

 the centre of the leaf, as is ufual in the fpecics 

 of this divifion. 



When the plants grow old, they fum.etimes extend 

 themfclves to the breadth of four or five inches, 

 and arc divided into deep unequal fegments, as 

 Micheli has figured it in the pkte above quoted, 

 and Dillenius in his Hifi. ■mujc. t. xo. f.iii. J. 



When the plant is wet it turns to a dull fufcous 

 green colour. 



