PAPENFUSS: CLASSIFICATION OF THE ALGAE 159 



With few exceptions (e.g., Pyrocystis) the Pyrrophycophyta which had be- 

 come known to science previous to 1912 were flagellated forms. In that year 

 Klebs published his significant discovery of several nonmotile unicellular organ- 

 isms that at certain stages in their development clearly revealed their relation- 

 ship to the dinoflagellates. 



Two years later Pascher (1914) not only announced the discovery of a num- 

 ber of additional nonmotile types but proposed a far-reaching revision of the 

 classification of the dinoflagellates. He erected a phylum Pyrropliyta and ac- 

 credited it with the three groups Cryptophyceae", Desmokontae, and Dinophy- 

 ceae. The Dinophyceae received, in addition to the characteristic flagellated 

 forms with dinoflagellate organization, those nonmotile genera with Gymnodi- 

 nmm-like swarmers that had been discovered by Klebs and himself. Some of 

 these forms had a palmelloid organization (his Dinocapsales), others had a coc- 

 coid organization (his Dinococcales), and the single representative of a third 

 group had a filamentous organization (his Dinotrichales). 



The Desmokontae included the forms which lacked a dinoflagellate organiza- 

 tion throughout their life history. They were divided into the two orders Des- 

 momonadales and Desmocapsales, the Desmomonadales receiving the four fami- 

 lies Desmomonadaceae, Exuviaellaceae {nomen nudum), Prorocentraceae, and 

 Dinophysiaeeae and the Desmocapsales accommodating the monogeneric family 

 Desmocapsaceae. 



Knowledge of the pyrrophyeophytes has progressed by great strides during 

 the past forty years. Space permits the consideration of but a few of the many 

 investigations that have contributed to this advancement. 



For our knowledge of the parasitic dinoflagellates we are especially indebted 

 to Chatton, who in 1920 published an extensive monograph on the morphology 

 and taxonomy of these forms. Some of them are ectoparasites, others are endo- 

 parasites, mostly on marine metazoa. Although these species bear little resem- 

 blance to ordinary dinophycids, their relationship to them is clearly revealed 

 by the structure of the motile reproductive cells. 



In a long series of publications, Kofoid and his associates contributed signifi- 

 cantly to our knowledge of the motile dinophycids. In 1921 Kofoid and Swezy 

 produced a monograph on the unarmored forms, based mostly upon their obser- 

 vations of living material obtained in the vicinity of La Jolla, California. They 

 described a number of new families and genera and presented a revision of the 

 classification of Dinophyceae. Kofoid and Swezy did not follow Pascher (whose 

 paper of 1914 they did not refer to) in the separation of the terminally bi- 

 flagellate forms into a separate group, the Desmokontae. They regarded the 

 Dinoflagellata as a subclass of the class Flagellata in the phylum Protozoa and 

 treated the terminally biflagellate forms as an order Adiniferidea of this sub- 

 class. The forms with "dinoflagellate" motile cells they placed in an order 

 Diniferidea. 



With few exceptions, the genera which Pascher placed in his orders Dino- 

 capsales, Dinococcales, and Dinotrichales were not considered by Kofoid and 

 Swezy. In fact they regarded (p. 109) the genera described by Klebs (1912), 

 namely, Phytodinium, Tetradinium, Stylodinium, and Gloeodinium, as more 

 nearly related to the green algae than to the dinoflagellates. 



7. The Cryptophyceae are now excluded from the phylum. 



