PAPENFUSS: CLASSIFICATION OF THE ALGAE "163 



furrow. The cells usually contain one contractile vacuole. Reserve food is deposited as 

 starch or starchlike compounds. Many of the Zooxanthellae growing symbiotically in 

 the tissues of radiolarians and corals are members of this class. 



History: Knowledge of the Cryptophyceae begins with the year 1832, when 

 Ehrenberg described Cryptomonas and Chilomonas. In 1838 he erected for Cryj)- 

 tomonas (and certain other forms which have since been shown to belong else- 

 where) tlie family Crj'ptomonadina, and referred it to his group 'Tolygastrica 

 anentera." 



Dujardin (1841, p. 270) placed the cryptomonads along with a number of 

 other flagellated organisms in his order "Infusoires pourvus d'un ou plusieurs 

 filaments flagelliformes servant d'organes locomoteurs. — Sans bouche," for which 

 group Cohn (1853) later proposed the designation Flagellata. 



The cryptomonads retained their position in the Flagellata for a long time 

 (Stein, 1878; Blitschli, 1883-1887; Klebs, 1892; Senn, 1900; Lemmermann, 1907- 

 1910). Various early authors (e.g., Cienkowsky, 1870; Schmitz, 1882; Dan- 

 geard, 1889) regarded them as algae, but general acceptance of them as a group 

 of plants begins with the year 1900 when Senn gave a treatment of them in 

 Engler and Prantl's Natilrlichen Pflanzenfamilien. 



Xlebs (1892, p. 392) circumscribed the group Flagellata in such a way that 

 it included only the five subgroups Protomastigina, Polymastigina, Euglenoi- 

 dina, Chloromonadina, and Chromomonadina. The Chromomonadina comprised, 

 according to his system, the two families Chrysomonadina Stein and Crypto- 

 monadina Ehrenberg. Although he placed these two families of essentially 

 yellow-brown organisms in a common group, Klebs emphasized that the crypto- 

 monads stood well apart from the chrysomonads. He especially drew attention 

 to the fact (p. 420) that the cryptomonads stored starch, which was not known 

 to occur in other Flagellata (according to his circumscription of this assem- 

 blage), and in this respect agreed with the dinoflagellates. 



Klebs regarded the Flagellata as standing intermediate between plants and 

 animals and believed they were the progenitors of various other lower organ- 

 isms. He was impressed by the prominent plantlike features of many members 

 of his group Chromomonadina and said (p. 278) that one could refer to them 

 as chrysophytes, a designation that was later formally adopted by Pascher 

 (1914) as the phyletic name for the chrysomonads, heterokonts, and diatoms. 



In agreement with Klebs (1892), Pascher in 1911 (b) believed in an alliance 

 between the cryptomonads and the chrysomonads, but he also pointed to the 

 possibility of a relationship between the cryptomonads and the dinoflagellates, 

 a view which had been held previously by Bergh (1881) and Blitschli (1883- 

 1887, 1885). In fact, Ehrenberg in his day had placed Prorocentrum in his 

 family Cryptomonadina. Pascher finally in 1914 removed the cryptomonads 

 from the vicinity of the chrysomonads and placed them as a group, Cryptophy- 

 ceae, along with the Desmophycidae and the Dinophycidae in the newly erected 

 phylum Pyrrophyta. 



Fritsch (1935), Smith (1938), Pringsheim (1944), Graham (1951), and 

 others have accepted the class Cryptophyceae but various authors, especially 

 Pringsheim and Graham, have been skeptical of its presumed relationship with 

 the Dinophyceae. Graham has in fact removed the class from the Pyrrophyco- 

 phyta — primarily on the basis of the difference in nuclear structure. 



