4. Cells spherical — 5 



4. Cells broadly or narrowly fusiform 6 



5. Mother cell splitting into 2 persisting sections 



to release 2 or 4 autospores Diachros 



5. Mother cell sections not persisting after release of autospores; auto- 

 spores 2-4, usually numerous; cells solitary Botrijdiopsis 



6. Cells broadly fusiform, irregularly ovate - Pleurogaster 



6. Cells narrowly fusiform, needle-shaped or sickle-shaped, 



curved, sometimes twisted - Chlorocloster 



7. Cells tetragonal or triangular 8 



7. Cells globose, ovate, or fusiform 9 



8. Cells tetragonal Tetragoniella 



8. Cells flattened, 3- or 4-angled - Goniochloris 



9. Cells spherical 10 



9. Cells oblong, ovate, or fusiform — - — 11 



10. Cells sculptured with circular depressions 



and a reticulum Arachnochloris 



10. Cells bearing long or short spines — Meringosphaera 



11. Chromatophores 1- or 2-lobed, parietal 



plates, often forming H-shaped bands ..Trachychloron 



11. Chromatophores several broad, parietal discs or bands Chlorallanthus 



ARACHNOCHLORIS (Pascher) Pascher 1939, p. 480 

 Cells spherical, solitary, with walls sculptured by broad circular 

 or elongate depressions, sometimes faint, producing serrations at the 

 wall margin; membrane becoming silicified in age; chromatophores 

 2 or several bands or petal-like plates arising parietally from a 

 thickened common center, sometimes forming H-shaped plates 

 wrapped along the cell wall, a pyrenoid sometimes evident; storage 

 products fats and leucosin; reproduction by autospores or by hetero- 

 kont zoospores formed 2-4 in a cell. 



Arachnochloris minor Pascher 1930, p. 412 

 PI. 95, Figs. 9, 10 

 Cells spherical, the wall firm, finely sculptured (sometimes in- 

 distinctly) with closely arranged series of depressions; basal body 

 of chromatophore spongy, with an indistinct pyrenoid; chromato- 

 phore forming 2 parietal lobes; red oil drops sometimes present; cells 

 '7-9/A in diameter. 



Little Lake Sixteen, Presque Isle County, Michigan, an acid 

 Sphagnum bog habitat. 



BOTRYDIOPSIS Borzi 1894, p. 169 

 Cells solitary (or incidentally clustered in families), spherical or 

 compressed-globose, the walls thin and in 2 overlapping sections; 



[349] 



