36 



MKSOZOIC VXD CAINOZOIC DINOFLAGELLATE CYSTS 



terminating with a small bifurcation. Number and size of sutural processes varying 

 considerably, up to three between adjacent gonal processes. Sutural crests proximal 

 or well developed and always extending along gonal processes, making the latter 

 subcorneal in shape. When the crests are well developed, the sutural processes may 

 be reduced to delicate protuberances emanating from the crest border. 



Holotype. B.M.(N.H.) slide ¥.51981(1). Metropolitan Water Board Borehole 

 No. 11 at 63 feet depth, London Clay ; Enborne, Berkshire. 



Dimensions. Holotype : diameter of central body 35 by 44-5^, length of 

 processes up to 14^. Range of London Clay specimens ; diameter of central body 

 35-59PL, length of processes up to i6}jl Number of specimens measured, 6. Range 

 of Hauterivian and Barremian specimens ; diameter of central body 34-47^. 

 Length of processes up to I2(x. Number of specimens measured, 7. Range of 

 Cenomanian specimens ; diameter of central body 31-46^, length of processes up to 

 i9[x. Number of specimens measured, 11. 



Remarks. H. ramosa var. multibrevis is characterized by the presence of short 

 gonal and sutural processes. Examples from the Lower Cretaceous possess very 

 short, rather rudimentary processes and differ from H. dentata (Gocht 1959) in 

 having the characteristic tabulation of the genus which is lacking in Gocht's species. 

 In the Cenomanian the processes are better developed but rather variable in form, 



Fig. 9. Hystrichosphaera ramosa var. multibrevis nov. A specimen from the London Clay. 

 Left, ventral view. Plate 3" (the operculum of the archaeopyle) lies within the central 

 body. Right, dorsal view. x c.1500. 



