PAPENFUSS: CLASSIFICATION OF THE ALGAE 145 



the skeleton of the cells. The isolated eoccoliths occurring in the ooze repre- 

 sented, in his opinion, the remains of disintegrated cells. Wallich called the 

 cells coccospheres and thought they were developmental stages of Foraminifera. 



A few years later, Wallich (1865, p. 81, fn.; 1869) announced that he had 

 obtained living coccospheres in surface waters of the sea. But it was not until 

 1877 that he proposed a generic name {Coccosphaera) for his coccospheres and 

 credited the genus with two species. 



"Wallich and various early authors believed that these organisms Avere color- 

 less. J. Murray (1891, p. 257) and Haeckel (1894, p. 110) considered them 

 algae, although they had no adequate foundation for their belief. G. Murray 

 and Blackman (1898) observed that the coccospheres contained a yellow-green 

 pigment and thus furnished the first proof of their algal nature. They believed 

 that the cells possessed a single chromatophore, but it was later shown by Loh- 

 mann (1902) and others that two plastids were present. 



On the basis of a study of living material from the Mediterranean, Loh- 

 mann (1902) gave the first monographic treatment of the group, together with 

 an account of the history of the complex up to the time of his writing. He was 

 the first to observe that the cells were provided with one (as he believed) or two 

 equal flagella. (Schiller, 1925a, p. -42, later found that all the flagellated species 

 possess two equal flagella.) 



Lohmann (1902, p. 125) concluded that the Coccolithophorineae shared 

 more characters with the chrysomonads than with any of the other large groups 

 of flagellates, and he had little hesitation in placing them in this group. Since 

 the name Coccosphaera, proposed for the flrst genus by Wallich, was preempted 

 by Coccosphaera Perty, Lohmann (p. 93) substituted the very appropriate ge- 

 neric name Coccolithophora and erected the family Coccolithophoridae, by which 

 designation the group as a whole has since been known. 



Although Lohmann was aware of the long known freshwater genus Hymeno- 

 monas Stein (1878), which also forms calcium carbonate plates on the cell sur- 

 face, he failed to recognize it as a member of the Coccolithophorineae. The 

 relationship between this genus and the marine representatives of the group 

 was first pointed out by Conrad (1914). 



The majority of more recent students of the Coccolithophorineae (e.g., 

 Conrad, 1926; Kamptner, 1928; Schiller, 1930; Huber-Pestalozzi, 1941) have 

 regarded the group as belonging to the Chrysophyceae, although Schiller (1930, 

 p. 147), in agreement with Schussnig (1925), considers them sufficiently dis- 

 tinct from other Chrysophyceae to warrant placing them in a separate subclass. 

 In agreement with Conrad (1926), Fritsch (1935) and Iluber-Pestalozzi (1941), 

 the group is here considered as representative of the order Isochrysidales, which 

 is comprised of motile unicellular forms with two equal flagella. It should be 

 pointed out, however, that Schiller (1926) has shown that a few genera ap- 

 parently lack flagella. 



The most comprehensive monograph of the group is that bj^ Schiller (1930) 

 which appeared as part of a volume in Rabenhorst's Kryptogaynen-Flora . . . Al- 

 though a great majority of the species are marine in occurrence, forming a very 

 important component of the phytoplankton, a number of freshwater species 

 have become known. The classification of the complex here adopted is essen- 

 tially that of Schiller. 



