MESOZOIC AND CAINOZOIC DINOFLAGELL ATE CYSTS 



B 



Fig. i. Oligosphaeridium vasiformum (Neale & Sarjeant), a typical chorate cyst, showing 

 the presumed method of cyst formation, a. The probable original tabulation of the 

 dinoflagellate, which corresponds to that of Gonyaulacysta. (The apical tabulation is 

 wholly speculative.) b, The cyst forming within the dinoflagellate theca, attached to the 

 cell membrane by its processes, c, The abandoned cyst as found, with an apical archaeo- 

 pyle. [After Sarjeant (1965) reproduced by permission of the Editor of " Endeavour ".] 



