106 
although Ralfs himself placed this genus (as a sec¬ 
tion) in Fenium^ ”because the conjugated state, occuring 
so rarely, would seldom enable the student to distin¬ 
guish between Penium and Cylindro cystisk After the 
separation of Cylindrocystis Menegh. and Netrium 
(Næg.) Lütkem., the genus Penium has its characters 
as they were laid down by Lütkemüller (in Cohn’s 
Beitr. z. Biol. d. Pfl. 8, 1904 and in Verb. zooL 
bot. Ges. Wien 55, 1905). 
Ralfs separated 1844 the genus Tetmemorus 
from Olosterium. 
Concerning Bambusina Kütz. 1845 consult 
Giymnozyga Ehrenb. 1841! 
Glæoprium Berkel. 184:b = Hy alotJieca Ehrenb. 
1841. 
Goniocystis Hass. 1845 is identical with 
Staurastrum Meyen sens. lat. 
Holocystis Hass. 1845 was united with Mier as- 
terias by Ralfs 1848 and has since then been regar¬ 
ded as a proper genus onl}^ by very few authors 
(Wallich, Bennett), but as a subgenus by Tur¬ 
ner 1893. 
Isthmosira Kütz. 1845 contains two species^ 
which he did not place under their old genera. One 
of them, vertebrata^ ought to have been regarded by 
him as a Sphcerozosma^ but he seems not to have 
approved of this genus of. Cor da perhaps because a 
diagnose was missing. For the second, filiformis^ he 
ought to have used Corda’ s name Diplarthrum (sec¬ 
tion under Sphcerozosma). Cfr. above under Splice- 
rozosma ! 
. Phycastrum Kütz. lS4:b--= Staurastrwn Meyen 
sens. lat. 
Pithiscus Kütz. 1845 is a curious alga accor¬ 
ding to the description , (”— einer länglichen, in der 
Mitte halbirten, prismatischen Doppel-Zelle, wovon die 
innere symmetrische Palten oder Einbiegungen zeigt.”), 
