PALMELLACE^. 119 



Fronds attached at base, one or two feet long, from one to four lines in diameter, 

 very much and irregularly branched ; branches scattered or crowded, simple or divided, 

 a foot or more in length, attenuated to a fine point, sometimes smooth and naked, but 

 generally densely clothed with slender, villous ramenta, spreading to all sides. The 

 gelatinous tubes or sheaths in which the cells are seriated are very obvious, and lie close 

 together in longitudinal, parallel strata. The cells are of large size, bright-green colour, 

 and variable shape ; some are twice as long as others. 



This I had at first supposed to be a new species, but now regard it as a very gigantio 

 state of H. penicillatus, Ag. which under various forms and of various sizes is common 

 in alpine streams in Europe. I fear characters derived from the shape and size of the 

 cellules are not more to be depended upon than are those taken from the ramification. 



