KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 



81 



group as a whole may be traced out witli the widest gaps near the beginniug of 

 the series (figs. R, S). 



The fact tliat ]jotli Wysotzkia and Protoclirysis are fresh- water forms 

 renders it liighly improbable that these particular genera are to be considered 

 immediately in the direct line of evolution. They can be only persistent morph- 

 ological types, significant in structure of the common ancestral marine t\'pes 

 from which both they and the marine genera have been derived. 



Fig. E. Derivation of the dinoflagellates. 1. Wysot~l-ia bicUi<ita (Wys.) Lemm. After Cavers (1913, 

 fig. 7,). 2. Protodiiiifer tentaculatum sp. nov. .3. Oiyrrhis marina Bujarilin. After Senn (1911, pi. 30, fig. 9). 

 4. Hemidinium 7iasutum Stein. After Stein (1883, pi. 2, fig. 25). 5. naplodinium antjoliense Klebs. After 

 Klebs (1912, fig. 1 A). 6. Exuviaella marina Cienkowski. After Sehutt (1895, pi. 1, fig. 1-). 7. Prorocentrum 

 micans Ehrbg. 



So far as present knowledge goes the Dinoflagellata .of today probably 

 represent the terminal twigs of the phylogenetic branching (fig. S) of some 

 such simple flagellate, and the genera cited are not intermediate stages leading 

 on to more highly developed forms. 



The attempt to find cilia te affinities for the genus Polylxfikos grew out of a 

 misinterpretation of the structural relations of that remarkable organism. 

 Biitschli (1885rt) and later Bergh (1881/>), noting the presence of more than 

 one nucleus, with slight variations in size among them, correlated them with 

 the nuclei of the Ciliata as macronuclei and micronuclei. Cavers (1913) further 

 states that "whether Polijkrikos foi-ms a link Ijetween the Peridiniales and the 

 ciliate Infusoria is, of course, an open question in the absence of further transi- 

 tional t^-pes." Our own work on this genus confirms that published earlier by 



