MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 35 



Holotype. B.M.(N.H.) slide ¥.51757(1). 5 feet above the base of London 

 Clay ; Sheppey, Kent. 



Dimensions. Holotype : diameter of central body 35 by 43fi., length of processes 

 17-23^. Range of London Clay specimens ; diameter of central body 32-61- 5[x, 

 length of processes up to 29[x. Number of specimens measured, 7. Range of 

 Cenomanian specimens ; diameter of central body 28-33^, length of processes up to 

 20;j,. Number of specimens measured, 3. 



Remarks. H. ramosa var. gracilis is characterized by the slender, relatively long, 

 gonal and sutural processes. The position of the sutural processes in the examples 

 studied appears to be haphazard. 



The known stratigraphic range of this variety is from the Cenomanian (England) 

 to the Miocene (Australia). 



Hystrichosphaera ramosa var. granosa nov. 

 PL 4, fig- 9 



Derivation of name. Latin, granosus, granular — with reference to the granular 

 nature of the surface of the central body. 



Diagnosis. A variety of H. ramosa (Ehrenberg) similar to H. ramosa var. 

 gracilis except that the surface of the central body is coarsely granular. Height of 

 granules ranging up to o-5[x. 



Holotype. B.M.(N.H.) slide ¥.51752(2). 78 feet above the base of London 

 Clay ; Sheppey, Kent. 



Dimensions. Holotype : diameter of central body 35 by 42^, length of processes 

 up to 19^. Range : diameter of central body 33-45^, length of processes up to 

 io,[a. Number of specimens measured, 4. 



Remarks. A small number of specimens have been observed in the London 

 Clay that apparently do not possess sutural processes. However, there is a com- 

 plete gradation from these forms to those bearing many sutural processes and so 

 separation solely on this characteristic was not thought to be practical. 



H. ramosa var. granosa has only been recorded from the London Clay of England. 



Hystrichosphaera ramosa var. multibrevis nov. 

 PL 1, fig. 4 ; PL 4, fig. 6 ; Text-fig. 9 



1955. Hystrichosphaera furcata (Ehr.) ; Valensi : 586, pi. 4, fig. 4 ; pi. 5, fig. 12. 

 1958. Hystrichosphaera furcata (Ehr.) ; Eisenack : 406, pi. 25, figs. 4-8. 



Derivation of name. Latin, multus, much; brevis, short — with reference to 

 the large number of short processes present in this variety. 



Diagnosis. A variety of H. ramosa (Ehrenberg) with smooth or slightly reticulate 

 central body bearing short solid processes less than half the diameter of central body 

 in length. Gonal processes trifurcate, sutural usually bifurcate, both types usually 



