2I 5 
Classification of Green Algcz. 
Fam. II. Zygnf.mace^e. 
Chromatophores two , one placed on each side of the central 
nucleus, each consisting of a rounded bod;/ containing a pyrenoid. 
Akinetes sometimes formed. 
0 
Genera. 
1. Zygnema. Agardh, 1824. 
Chromatophores with radiating processes. Conjugation 
isogamous or anisogamous. 
2. Pyxispora. West and G. S. West, 1897. 
Vegetative cells indistinguishable from Zygnema. 
Conjugation isogamous. Zygote elliptical, with an 
equatorial ridge bearing a groove, and with its long axis 
perpendicular to long axis of conjugating filaments, 
3. Plcurodiscus. Lagerheim, 1895. 
Chromatophores disc-shaped, parietal or somewhat 
excentric. Cell-sap often purple. 
4. Zygogonium. Kiitzing, 1843. 
Chromatophores irregular, sometimes uniting into a 
single axile body. Cell-sap sometimes purple. Con¬ 
jugation isogamous. 
Fam. III. Mougeotiaceas. 
Ch romatophore single, consisting of a longitudinal axile plate 
with a single row of pyrenoids; sometimes almost divided into two in 
the middle of the cell. Cells much longer than broad. 
Genera. 
1. Mougeotia. Agardh, 1824. 
Tranverse walls lens-shaped. Part of protoplasm of 
the conjugating cells not used in the formation of the 
gametes. Zygote formed in the conjugation-canal, 
but sometimes extending right across one or both 
of the two conjugating cells. 
2, Mougeotiopsis. Palla, 1894. 
Like Mougeotia, but pyrenoids absent. 
3- Dcbarya. Wittrock, 1872. 
Like Mougeotia , but all the protoplasm of the conju¬ 
gating cells used to form the gametes Zygote formed 
in the conjugation canal, its brown middle membrane 
bearing three parallel ridges connected by striae. 
4. Teninoganietum. West and G. S. West, 1897- 
Like Mougeotia, but gamete-mother-cells short, specially 
cut off from vegetative cells. 
