224 MESOZOIC AND CAINOZOIC DINOFL AGELLATE CYSTS 



fashion, sometimes by trabeculae, sometimes by perforated membranes. Erect 

 unconnected secae, acuminate or bifid distally, arising from outer margin of trabecu- 

 lae or membranes. Length of processes rarely exceeding one-third the diameter of 

 the central body. 



Holotype. B.M.(N.H.) slide ¥.51956(2). London Clay ; Whitecliff, sample 8. 



Dimensions. Holotype : diameter of central body 54 by ji[L. Observed range : 

 diameter of central body 45-711X. Length of processes up to I5fx. Number of 

 specimens measured, 5. 



Description. The central body has a finely reticulate surface and is formed from 

 the extremely thin endophragm. The periphragm gives rise to the taeniate processes. 

 The numerous processes are restricted to the ambitus of the central body save on the 

 precingulars, where the processes surround the archaeopyle margin. The processes 

 are short, with only a few distal interconnctions. They tend to exhibit a linear 

 orientation and are often united proximally. The secae, arising from the distal 

 margin of the trabeculae or membranes that unite the processes, often appear to be 

 continuations of the processes distally, whilst at other times they arise at points 

 distant from the processes. Occasional simple acuminate processes are present on 

 the central body. 



Occurrence. Eocene, London Clay ; Whitecliff, Enborne, Sheppey and 

 Studland. 



Remarks. C. divaricatum differs from other described species of Cyclonephelium 

 in the nature of the processes distally and the point of origin of the trabeculae or 

 interconnecting membrane. 



OPERCULUM 

 / 



Fig. 60. Cyclonephelium divaricatum sp. nov. Partial drawing of specimen 

 showing operculum separating from the test. 



