241 
Classification of Gree7i Algce. 
lunar and has two diverging horns. Chromatophore 
parietal with a single pyrenoid. Daughter-ccenobia 
arise by two crossing radial divisions of each cell. 
Plcurothamnion. Borzi, 1895 . To follow Gongrosira , p. 165 . 
Closely resembles Gongrosira , but the zoosporangia 
arise in groups as a result of division of vegetative 
cells, and each contains only four to eight zoospores. 
Roya. West and G. S. West, 1896 . To follow Closterium , p. 190 . 
Differs from Closterium by the cells not tapering at the 
ends, by the absence of terminal vacuoles, and by the 
position of the nucleus close to the lateral wall. 
Sphocrocystis. Chodat, 1897 . To precede Palmodactylon , p. 72 . 
Colonies spherical, the cells varying in number from one 
to several hundred. Multiplication by division of the 
cells to form different daughter-colonies, and also by 
zoospores. 
Tetrasporidium. Moebius, 1893 . To follow Tetraspora, p. 69 . 
Thallus a floating, spongy, mucilaginous colony, with 
numerous irregular perforations and processes pro¬ 
duced by unequal distribution of celf division; 
Reproduction by swarmers, formed from only part 
of the protoplasm of the mother cell, and leaving a 
periplast behind. Flagella not observed. 
BIBLIOGRAPHY 
containing references to the genera published since the appearance of 
Wille’s “ Conj ugatae ” and “ Chlorophyceae ” ( 1890 ) in Engler and 
Prantl’s “ Natiirlichen Pflanzenfamilien.” 
A few references to fundamental work published since 1890 on genera 
of prior date are given in square brackets. 
Acanthosphcera. Lemmermann, Forschungsberichte der Biolog. 
Stat. zu Plon, 1899 , Teil 7 , p. 118 , Taf. I, 
figs 10 and 11 . 
[Aphanocliaete (reproduction of). Huber, Bull. Soc. Bot. France, 
1894 , Tome xli, p. xciv, pi. vii.] 
Askenasyella. Schmidle, Hedwigia, 1902 ., Bd. xli., p. 154 ., Fig. 
B, 1 - 3 . 
Bohlinia. Lemmermann, Forschungsberichte der Biolog. Stat. zu 
Plon, 1899 , Teil 7 , p. 120 , 
