1920] SetchelJ^Gardner: Chlorophyceiae 143 



Order 1. PROTOCOCCALES (meneghixi) oltmanns 



Unicellular isokontae, motile or iionmotile, often occurring singly 

 or in larger or smaller, definite or indefinite colonies or coenobia, or 

 even simple coenocytes, often provided with mucilaginous teguments 

 of more or less ample dimensions and of various shapes, never properly 

 multicellular; number and shape of chromatophores (chloroplasts) 

 various ; pyrenoids often present ; reproductive methods various as 

 outlined for the series Isokontae. 



Protococcales Oltmanns, Morph. und Biol, der Algen, vol. 1, 1904, 

 p. 169 ; West, Algae, vol. 1, 1916, p. 160. Protococcoideae Meneghini, 

 Cenni sulla organ, e. fisiol. delle Alghe, 1838, p. 4 (of reprint) ; Black- 

 man and TaiLsley, Revis, Class. Green Algae, 1902, p. 21 ; Wille, in 

 Engler and Prantl, Natiirl. Pflanzenfam., Nachtr. zum 1 Th., 2 Abt., 

 1909, p. 3. 



The Protococcales, or Protococcoideae as they have long been 

 designated, form a rather large and seemingly heterogeneous order. 

 They are mostly inhabitants of the fresh waters and, although unicel- 

 lular in the broad sense, are varied in their form, aggregation and 

 methods of reproduction. Our marine species are few so far as 

 known, but undoubtedly a considerable number yet remain to be 

 detected. This is particularly true of the endophytic species of our 

 coast whose presence and development are very little understood at 

 present. 



Key to the Families 



1 . Thallus of larger or smaller colonies (or aggregations of cells) 



1. Palmellaceae (p. 143) 



1. Thallus strictly unicellular 2. Chlorochytriaceae (p. 146) 



FAMILY 1. PALMELLACEAE ■^^aH^isaE-^ naegeli 



Cells united into larger or smaller colonies by mucilaginous modi- 

 fication of the outer walls, usuall^^ provided with a single parietal 

 chromatophore (chloroplast) containing a single pyrenoid; repro- 

 duction hy biciliated zoospores or by isoplanogametes ; fragmentation 

 of colonies often takes place. 



Palmellaceae Naegeli, Die neuern Algensyst., 1847, p. 123; West, 

 Algae, vol. 1, 1916, p. 183. Palmelleue Decaisne, Essai sur une classe 

 des Algues, etc., 1842, p. 327. 



