go MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 



Processes taeniate, solid, undulose with serrate or digitate distal margins, sometimes 

 arranged in meridional rows, sometimes haphazard in position. 



Holotype. B.M.(N.H.) slide ¥.51751(1). 173 feet above base of London Clay ; 

 Sheppey, Kent. 



Dimensions. Holotype : diameter of central body 56 by 59fA, length of processes 

 up to i5[i. Range : diameter of central body 45-59^., length of processes up to 24^. 

 Number of specimens measured, 4. 



Description. The processes are numerous, generally simple with parallel edges 

 expanding proximally and distally. Some of the processes are regularly linked 

 proximally in such a manner as to give rise to six long rows, running from apex to 

 antapex. Between these rows the arrangement of the other processes appears to be 

 haphazard. There appear to be 2, rarely 3, processes per plate area. The maxi- 

 mum width of the processes is j\l, and their length one-quarter to one-third (rarely up 

 to one-half) the diameter of the central body. Occasionally fine, acuminate proces- 

 ses are present on the central body. There is a well developed archaeopyle with an 

 uninterrupted margin. 



C. multispinosum sp. nov. has been recorded from the London Clay of Whitecliff 

 Bay, Isle of Wight, Hampshire and the Isle of Sheppey, Kent. 



Remarks. In the linear arrangement of some of the processes and the haphazard- 

 ous nature of others C. multispinosum differs from all other species of Cordosphae- 

 ridium. 



?Cordosphaeridium fasciatum sp. nov. 

 PI. 7, figs. 5, 6 



Derivation of name. Latin, fasciatus, striped — with reference to the striped 

 appearance of the central body due to the thickenings of the periphragm. 



Diagnosis. Spherical to sub-spherical central body composed of reticulate 

 endophragm of fibrous periphragm. Processes, composed of periphagrm, smooth or 

 slightly fibrous, short, wide and tubiform, always hollow and denticulate distally. 



Holotype. B.M.(N.H.) slide ¥.51719(1). Speeton Clay, Shell West Heslerton 

 Borehole No. 1, Yorkshire, at 42-5 metres depth. Lower Cretaceous (Lower 

 Barremian). 



Dimensions. Holotype : diameter of central body 40 by 40(0., length of processes 

 n-i6fx, number of processes 19. Range : diameter of central body 35-47(a, length 

 of processes 12-25^. Number of specimens measured, 6. 



Description. From the base of each process, thickenings of the periphragm 

 radiate over the surface of the central body joining together with similar thickenings 

 from neighbouring processes. The reticulate nature of the endophragm can some- 

 times be observed where the periphragm thins midway between processes and also at 

 the bases of the processes when one is able to view directly down the centre of a 

 vertical process (PI. 7, fig. 6). The processes have parallel or sub-parallel sides 



