IIG 



Fam. VII. CEMTOFllOHEM. 



Char. Alg£C rjelatmons, ramose, composed of jirincipal stems 

 and smaller filaments, for the most part ciliated. Re- 

 production usually by means of zoospores contained in the 

 filaments, hut in some cases said to be capsular. 



The species of this very natural family accord with the 

 preceding in being composed of two sets of filaments, in their 

 extreme lubricity, and in their branches terminating in long 

 ciliform appendages, to which, in a measure, their great 

 lubricity is attributable. They differ from it, however, in 

 the secondary branches not being whorled, in the absence of 

 glomerules, and of the fibrillar surrounding the primary cells, 

 also in being of a light and beautiful green colour, which, 

 in drying, does not change to some other tint, as has been 

 seen to be the case in the Batrachospermece. 



The two families, likewise, agree in habit, the Chceto- 

 lihorecR, like the BatrachospermecE, dwelling in fresh and pure 

 water, such as that of fountains and slow streams ; but on 

 account of the delicacy of their structure they are not met with 

 in large rivers or streams, the force of whose current is 

 strong, and which would sweep them away and destroy them. 



On certain species of the genus ChcRtophora capsules have, 

 from time to time, been met with, but the occurrence of these 

 is exceedingly rare, and it cannot be supposed that the ordi- 

 nary and usual mode of reproduction is by means of these. 

 The true reproductive bodies in this family, as well in all 

 probability as in that of the Batrachospermece, are undoubt- 

 edly zoospores. If a specimen o^ Draparnaldia, D. glomerata 

 for example, be examined microscopically in its young state, 

 the main filaments will be seen to be quite cylindrical : at a 

 later period, however, the cells, of which these filaments are 

 composed, swell up, and the filaments then become beaded. 

 This inflation of the cells, which occurs in almost all the 



