70 Veit Brecher Wittrock. 



lateral process belonging to the supporting cell, which circumstance is occasioned 

 by the fact that the transversal cell-wall, which has separated the branch process 

 first formed from its mother cell, has been formed somewhat higher up in the branch 

 process, not at its base. *) The top branches are often bent like a sickle. The 

 thickness ot the cells varies between 85 and 125 i.i. Their length is 7 — 25 times 

 greater than the thickness. 



According to D:r Grunow's opinion, directly communicated to me, both the 

 forms now mentioned belong to CJadophoni sumatrana v. Mart. (i. e. to Pithophora 

 sumatrana (v. Mart.) nob.) The one growing in brackish water D:r Grunow has 

 determined as being a variety under the name of fuscesccns. My opinion is also 

 that these forms are nearly related to F. sumatrana (v. Mart.) nob. Whether 

 they are quite identical with it can not be determined with certainty till they are 

 known in a fertile state. The form grown in fresh water calls to mind P. œqiialis 

 nob. almost more than P. sumatrana (v. Mart.) nob. 



^) The same ciroumstaace sometimes takes place in P. polpnorpha nob.; see pi. 1, 

 fiffs. 15 and 17. 



