160 ^ CENTURY OF PROGRESS IN THE NATURAL SCIENCE^ 



In 1928 Kofoid and Skogsberg published an extensive monograph upon the 

 dinoflagellates of the "Albatross" expedition. Three new families and five 

 new genera were described in this work. 



The most extensive systematic treatises on the pyrrophycophytes are those 

 of Lindemann, published in 1928 as a volume in the second edition of Engler 

 and Prantl's Pflanzenfamilicn, and of Schiller, published in two volumes be- 

 tween 1931 and 1933, and 1935 and 1937. Many of the currently accepted fami- 

 lies were established by Lindemann. The volumes by Schiller appeared as part 

 of the second edition of Rabenhorst's Kryptogamen-Flora von Deutschland, Os- 

 terreich und der Schweiz but their scope is much more comprehensive than the 

 title of the series suggests inasmuch as they treat of all the known living species. 

 Valuable general accounts of the phylum have recently been given by Fritsch 

 (1935) and Graham (1951). 



The classification presented in the synopsis below is a synthesis of the systems 

 of Pascher, Lindemann, Schiller, Fritsch, and Graham. This arrangement de- 

 parts in certain major respects from Pascher 's system and in conclusion it is 

 deemed desirable to review briefly the more significant points in the evolution 

 of this classification. 



It will be recalled that Pascher (1914, 1927a, 1931) accredited the Pyrro- 

 phycophyta with the three groups Desmokontae, Cryptophyceae, and Dinophy- 

 ceae. Fritsch (1935) treats the Cryptophyceae as a distinct class, which at best 

 may be only distantly related to the other two groups. Graham (1951) has 

 further emphasized the distinctness of the Cryptophyceae, especially as regards 

 the structure of the nucleus, and in agreement with him they are here consid- 

 ered as a separate class appended to the Pyrrophycophyta. 



Fritsch (1935) in agreement with many earlier workers, regards the Desmo- 

 kontae and the Dinophyceae of Pascher as more closely related than is implied 

 by Pascher's system and treats them as groups, Desmokontae and Dinokontae, 

 belonging to a common class, the Dinophyceae. 



Pascher (1914) accredited the Desmokontae with the two orders Desmomona- 

 dales and Desmocapsales. Fritsch (1935, p. 672) produces convincing reasons 

 for placing the single genus Besmocapsa, upon which Pascher based the Desmo- 

 capsales, in the family Desmomonadaceae of the order Desmomonadales. 



In the order Desmomonadales Pascher (1914) had placed four families, viz., 

 Desmomonadaceae, Exuviaellaceae, Prorocentraceae, and Dinophysiaceae. In 

 1928 Lindemann established the order Thecatales^ for the Prorocentraceae, leav- 

 ing the order in the Desmokontae (or Adiniferae as he called this group). Pas- 

 cher (1931), Schiller (1931), Fritsch (1935), and Graham (1951) have accepted 

 this order, except that Pascher and Graham call it Prorocentrales. 



Lindemann also established an order Dinophysiales for the Dinophysiaceae, 

 added to it a second family, the Amphisoleniaceae, and removed the order to the 

 Dinokontae (or Diniferae as he called this group). Pascher (1931), Schiller 

 (1931), who enriched the order with two more families, and Fritsch (1935) ac- 

 cept the order Dinophysiales but retain these forms in tlie Desmokontae. Graham 

 (1951, p. Ill), however, produces well-founded arguments for referring the 

 Dinophysiales to the Dinokontae, with which group Kofoid and Skogsberg (1928) 

 as well as Lindemann had related it. 



8. As "Klasse," but Liudemann's classes are actually all orders. 



