MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 



Genus Wetzeliella Eisenack 



Wetzeliella neocomica Gocht 

 Conclusions ...... 



XI. Further dinoflagellate cysts from the London clay (G. L 

 Williams & C. Dovvnie) .... 



Introduction ...... 



Genus Adnatosphaeridium nov. . 

 Adnatosphaeridium viltatiim sp. n. 



multispinosum sp. n. 

 patulum sp. n. . 

 Other Species ..... 



Genus Membranilarnacia Eisenack 



Membranilarnacia reticulata sp. n. 

 Genus Nematosphaeropsis Deflandre & Cookson 



Nematosphaeropsis balcombiana Deflandre & Cookson 

 Genus Cannosphaeropsis O. Wetzel 



Cannosphaeropsis reticulensis Pastiels 

 Genus Cyclonephelium Deflandre & Cookson 

 Cyclonephelium divaricatum sp. n. 



exuberans Deflandre & Cookson 

 ordinatum sp. n. 

 pastielsi Deflandre & Cookson 

 Genus Areoligera Lejeune-Carpentier . 

 Areoligera coronata (O. Wetzel) 



cf. coronata (O. Wetzel) . 

 cf. medusettiformis (O. Wetzel) 

 cf. senonensis Lejeune-Carpentier 

 Genus Deflandrea Eisenack 



Deflandrea phosphoritica subsp. phosphoritica Cookson & 

 Eisenack ...... 



subsp. australis Cookson & Eisenack 

 denticulata Alberti. 

 oebisfeldensis Alberti 

 wardenensis sp. n. . 

 Genus Thalassiphora Eisenack & Gocht 

 Thalassiphora pelagica (Eisenack) 

 delicata sp. n. . 

 XII. Acknowledgments ..... 



XIII. References ...... 



XIV. Index 



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SYNOPSIS 



The morphology of fossil dinoflagellate cysts is discussed ; the cysts are shown to fall into 

 three broad groups (" proximate ", " chorate " and " cavate "), which are interpreted as 

 indicating different modes of formation. New terms are proposed, to enable more precise 

 description of cyst morphology. The principal genera are reconsidered, in the light of new 

 information from studies of assemblages from the Cretaceous (Speeton Clay and Chalk) and 

 Eocene (London Clay) of England. 27 new genera are proposed and emendations are given to 

 the diagnoses of 16 existing genera ; 64 new species are described and the diagnoses of nine 

 existing species are emended. In addition, the generic allocation of other species already 



