98 



Ml SOZOIC AND CAINOZOIC DINOFL AGELL ATE CYSTS 



Genus TANYOSPHAERIDIUM nov. 



Derivation of name. Greek, tanyo, long or stretched out ; sphaera, ball — 

 with reference to the elongate nature of the central body exhibited by this genus. 



Diagnosis. Chorate cysts with elongate central body composed of endophragm 

 and periphragm, the latter also forming the processes. Processes cylindrical, open 

 distally and arranged in more or less regular circular manner around central body. 

 Number of processes variable, usually one or two (occasionally three) per plate area. 

 Archaeopyle apical. 



Type species. Tanyosphaeridium variecalamum sp. nov. Upper Cretaceous 

 (Cenomanian) ; England. 



Remarks. The marked feature of this genus is the elongate nature of the central 

 body. Although the processes are arranged in a distinct circular manner on the 

 surface of the central body, the tabulation is difficult to determine. The number of 

 antapical processes, however, appears to be 3 or 6. Usually there is one or two proces- 

 ses per plate area, but occasionally three may be present. Neither a detached apical 

 region nor a complete specimen has, so far, been observed. 



Tanyosphaeridium variecalamum sp. nov. 



PL 6, fig. 7 ; Text-fig. 20 



Derivation of name. Latin, varius, different ; calamus, reed — with reference 

 to the rather variable extremities of the processes. 



Fig. 20. Tanyosphaeridium variecalamum sp. nov. Holotype, lateral view, showing the 

 circular arrangement of processes around the central body. x c. 1450. 



