PAPENFUSS: CLASSIFICATION OF THE ALGAE 155 



Family Rhizosoleniaceae (Petit) De Toni (1890, p. 921) 

 Syn.: Soleniaceae (Scluitt) Karsten (1928, p. 202) 



Family Chaetoceraceae H. L. Smith orth. mut. De Toni (1890, p. 920) 



Family Biddulphiaceae Kiitzing orth. mut. De Toni (1890, p. 910) 

 Syn.: Isthmiaceae Cleve orth. mut. De Toni (1890, p. 913); Hemiauli- 

 daceae Heiberg orth. mut. De Toni (1890, p. 912) 



Family Anaulaceae (Schiitt) Hustedt (1930, p. 56) 



P'amily Euodiaceae (Schiitt) Hustedt (1930, p. 56) 



Family Rutilariaceae Pantocsek orth. mut. De Toni (1894, p. 1020) 

 Order PENNALES (Schiitt) West orth. mut. Karsten (1928, p. 202) 



Family Diatomaceae (S. F. Gray) Diimortier (1829, p. 77) 



Syn.: Fragilariaceae Kiitzing orth. mut. De Toni (1890, p. 905); 

 Meridionaceae Kiitzing orth. mut. De Toni (1890, p. 904); Trachy- 

 spheniaceae (Petit) De Toni (1890, p. 904) ; Plagiogrammaceae 

 (Petit) De Toni (1890, p. 906); Licmophoraceae Kiitzing ortli. mut. 

 De Toni (1890, p. 907); Striatellaceae Kiitzing orth. mut. De Toni 

 (1890, p. 907); Entopylaceae Grunow orth. mut. De Toni (1890, p. 

 909); Tabellariaceae Kiitzing orth. mut. West (1904, p. 281) 



Family Eunotiaceae Kiitzing orth. mut. Rabenhorst (1853, pp. vii, 8, 15) 



Family Achnanthaceae Kiitzing orth. mut. De Toni (1890, p. 900) 

 Syn.: Cocconeidaceae Kiitzing orth. mut. De Toni (1890, p. 899) 



Family Naviculaceae Kiitzing orth. mut. Rabenhorst (1853, pp. ix, 9, 36) 

 Syn.: Cymbellaceae Kiitzing orth. mut. De Toni (1890, p. 898); 

 Gomphonemaceae Kiitzing orth. mut. De Toni (1890, p. 899); Amphi- 

 tropidaceae (Pfitzer) De Toni (1890, p. 898) ; Amphipleuraceae Grunow 

 orth. mut. De Toni (1890, p. 902) ; Cocconemaceae West (1904, p. 298) 



Family Epithemiaceae Grunow orth. mut. De Toni (1892, p. 776) 



Family Nitzschiaceae Grunow orth. mut. De Toni (1890, p. 901) 

 Syn.: Cylindrothecaceae (Kirchner) De Toni (1890, p. 902) 



Family Surirellaceae Kiitzing orth. mut. De Toni (1890, p. 903) 



Phylum Pyrrophycophyta 



Characterization : This phylum as now delimited embraces the single class Dino- 

 phyceae which includes two somewhat dissimilar groups of largely unicellular organ- 

 isms, the subclasses Desmophycidae (desmokonts) and Dinophycidae (dinoflagellates, 

 peridinians). 



The Dinophycidae comprise forms which in the vegetative condition are (1) unicel- 

 lular and biflagellate,'' (2) unicellular and amoeboid, (3) unicellular, nonmotile, and in 

 the form of small gelatinous aggregates (palmelloid types), (4) unicellular and non- 

 motile, with a firm cell wall (coccoid types), or (5) in the form of multicellular attached 

 filaments. 



These diverse types share two prominent features which suggest that they constitute 

 a related assemblage. Firstly, the flagellated species and the motile reproductive cells of 

 the nonmotile forms exhibit what Graham (1951) calls a "dinoflagellate orientation." 

 In them the two flagella are inserted near each other and laterally on what is known as 

 the ventral side. One of the flagella is usually threadlike and projects backwards. At 

 its proximal end it lies in a ventral, longitudinal groove, the sulcus. The other flagellum 

 is ribbon-shaped and encircles the cell. It lies in a transverse or spiral groove, the girdle. 

 The second feature common to these organisms is found in the structure of the nucleus: 

 the chromatin is contained in threads which are distinctly beadlike and this character 

 persists throughout karyokinesis. 



Less distinctive features which the Dinophycidae share with the Desmophycidae 

 are: (1) the possession by the photosynthetic forms of a complex of pigments which 

 give them a greenish tan or golden brown color (where examined [Strain, 1951, p. 253] 



5. Polykrikos is colonial and each individual in the chainlike colony is furnished 

 with two flagella. Whether or not any of the cells are separated by transvei'se walls is 

 not clear from the literature. 



