MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 



Genus PROLIXOSPHAERIDIUM nov. 



171 



-with 



Derivation of name. Latin, prolixus, stretched out long ; sphaera ball- 

 reference to the shape of the central body. 



Diagnosis. Shell shape elongate ovoidal to ellipsoidal, one pole (apical) typically 

 lost in archaeopyle formation. Opposite pole occupied by one or two antapical 

 processes. Remaining processes arranged in distinct rows encircling test ; these 

 rows slightly offset at a position corresponding to sulcus. Number of processes 

 exceeding 30. Processes closed proximally, closed or open distally : their distal 

 terminations simple ; flaring in varied fashion ; or briefly furcate. Shell surface 

 bearing cover of coarse granules or very short, simple spinelets, or lacking such 

 ornamentation. 



Type species. Prolixosphaeridium deirense, sp. nov. Lower Cretaceous (Middle 

 Barremian) ; England. 



Remarks. A group of Mesozoic dinoflagellate cysts exhibit an elongate central 

 body with a terminal archaeopyle. Their distinctive character and unity of form 

 merits taxomonic recognition at generic level. The arrangement of the processes 

 suggests that they are intratabular, corresponding perhaps to crest nodes, but 

 prolonged study of many individuals would be necessary before this could be 

 confirmed. 



Prolixosphaeridium deirense sp. 



PI. 3, fig. 2 ; Text-fig. 45 



nov. 



Derivation of name. Latin, deirense, of Deira, the ancient kingdom occupying 

 what is now East Yorkshire. 



Fig. 45. Prolixosphaeridium deirense gen. et sp. nov. Left, ventral view ; 

 right, dorsal view. X c. 1000. 



