132 HELMINTHOCLADEiE. v. 



the periphery. These latter are generally moniliform, either elongated and free 

 one from another, or abbreviated and combined by firm gelatine into a thin mem- 

 Iji'ane. In the suborder Liagorece they are invested with a secretion of carbonate 

 of lime. 



The sporiferous nucleus is not contained within any conceptacle, but freely sus- 

 pended among the threads of the peripheric stratum, by which it is surrounded 

 and involucrated. It consists of a spherical ball composed of innumerable slender, 

 articulated, branching filaments radiating from a common central point, and bear- 

 in o- small, oval spores on the ends of the branches. Such is the structure in the 

 first suborder at least. In Scinaia, however, I think I have seen, under a highly 

 magnifying power, a cellular membrane as described by Montague, but denied by 

 Prof J. Agardh, investing the ball of spore-threads. Tetraspores have only been 

 observed in Nemalion, where they are formed in the terminal cellules of the peri- 

 pheric filaments. 



The close mutual relationship of the genera here associated will be generally 

 admitted ; with perhaps the exception of Scinaia, should the fact of its possessing 

 an external membrane to the nucleus be established. However this may be, the 

 internal structure of its nucleus bears a near resemblance to that of the typical 

 genera. The fructification of the Liagorece is not yet fully known, but the habit 

 and nature of the frond are so similar to those of the Gloiodadece thai there is nothing 

 to invalidate the juxtaposition, at least, of these Algas. Dudresnaia, Croiiania, and 

 Gloiosiphonia, which were formerly arranged among Gloiocladew, differ essentially 

 in the structure of the sporiferous nucleus, and are now properly placed by Prof 

 Agardh, the two former in Ceramiacea', the latter in Cryptonemiacece. In those 

 Orders they represent, by analogy, the present group. 



The geographical distribution of these plants is extensive. Of the five genera 

 yet known four are North American ; two of these, Hehninthora and Nemalion^ being 

 also European ; Liagora common to all tropical and sub-tropical regions ; and 

 Scinaia dispersed nortli and south of the equator through the Atlantic and Pacific 

 basins. Helminthocladia has, as yet, only been found in Europe. None are applied 

 in the arts. 



SYNOPSIS OV THE NORTH AMERICAN GENERA. 



Sub-order 1 . Gloioclade^. Periphery formed of moniliform filaments lying 

 in rather loose, transparent gelatine. 



I. Helminthora. Axis laxly cellular within (the interior filaments much dis- 



tended). Frond decompoundly much-branched. 



II. Nemalion. Axis cord-like, composed of closely interlaced, very slender filaments. 



Frond sparingly dichotomous. 



