728 CoDJugatae, Zygnemaceae, Zygnema. 



Kirchn. Alg. Schles. p. 125, Cooke Brit. Freshw. Alg. p. 76, Wolle 

 Freshw. Alg. U. S. p. 222, De-Toni e Levi Fl. Alg. Ven. III p. 68. 

 Gay Ess. Monogr. Conjug. p. 83!, Hansg. Prodr. p. 153. 



Zygogonium Kuetz. [1843] in Linnsea XVII p. 92, Phyc. gener. p. 280, 

 Kirchn. Alg. Schles. p. 127, Tyndaridea Hassall [1841] Mauual 

 p. 141, Tendaridea Bory [1832] Dict. class. I, p. 495, Thwaiiesia 

 Mont. [1838] Fl. d'A]gerie p. 175, SteUulina Link [1833] Handb. 

 ni, p. 261, Cxlobulina Link [1820] in Nees Hor. Phys. Berol. p. 4 

 nec Turpin, Ledae sp. Bory. nec Moug. et Nestl. 



Thallus filiformis, e cellulis cjlindraceis chlorophora ') 2 axilia, 

 prope nucleum centralem disposita, pluriradiata, pyrenoidem singu- 

 lum obvolventia includentibus constitutus ; membrana cellularum aut 

 tenuis, haud stratosa, aut crassa et stratosa. 



Propagatio cystis h. e. cellulis perdurantibus (aplanosporis) ^), zy- 

 gotis simillimis. 



Generatio zygotis: zygota intra unara alteramve cellularum con- 

 jugatarura vel in medio canalis conjugationis sita, mesosporio levi vel 

 rugoso-foveolato donata,- conjugatio scaliformis vel lateralis. 



I. Subgenus Euzygnema Gay Essai Monogr. Conjug. 1884 p. 84, Hansg. 

 Prodr. p. 153. 



Membrana cellularis tenuis , haud distincte stratosa ; chlorophora con- 

 spicua; conjugatio scaliformis vel lateralis ; zygota plerumque in cellula 

 feminea inclusa, mesosporio plerumque grosse foveolato praedita. 



Sectio 1. Leiospermum (De-Bary) Hansg. in Hedwigia 1888 p. 257: Membra- 

 na media zygotorum levis et homogenea. 



Subsectio I. Cyanospermum Hansg. in Hedwigia 1888 p. 257. 



Membrana media zygotorum globosorum vel subglobosorum chalybea vel 

 coerulea. 



j4. Zygota in una cellula scaliformiter cum altera cellula conjuganti 

 orta. 



1. Zygnema chalybeospermum Hansg. in Hedwigia 1888, p. 257 et 1735 

 in Notarisia 1889 p. 679. — Caespitibus laxe intricatis, Isete vel 

 flavo-viridibus, aetate provecta subolivaceo-virescentibus, minime 

 lubricis, in aqua rapide fluenti fluctuantibus vel in superficie aqua^ 

 libere natantibus; filis haud raro calce carbonata conspurcatis; cel- 

 lulis vegetativis, 24-27 ^. latis, diametro I ad 3-plo, fructiferis y^ 



') Chlorophora rarius in tseniam axilem insimul confluunt. 

 2) Cfr. Wille Algol. Mittheil. p. 497-499. 



