2l6 



MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 



length 28 (when archaeopyle present) to 52(1; Length of processes up to 3i[x. 

 Number of specimens measured, 4. 



Description. Adnatosphaeridium vittatum has strongly developed taeniate 

 processes, often exceeding I0[x in width, which may be arranged in linear, soleate, or 

 annular complexes. In outline, the complexes can be tubiform to flaring, distally 

 having two orthogonal or recurved branches. The outer margin of the branches is 

 frequently finely serrate. Branches of processes are interconnected with other 

 processes on the same or adjacent plates. The interlinking of processes gives to 

 them the appearance of natural arches. Some of the processes are simple and are 

 oblate or bifid distally. Occasionally hollow branched open processes are present on 

 the central body. Unconnected acuminate spines may arise from the processes. 



Occurrence. Eocene, London Clay ; Sheppey, Kent. 



Remarks. A. vittatum is characterized by its taeniate processes of varying width, 

 the presence of free and united processes and the occasional hollow branched proces- 

 ses. The distal serrate terminations are unusual in this genus. 



Adnatosphaeridium multispinosum sp. nov. 

 PL 24, fig. 5 ; Text-fig. 57 



Derivation of name. Latin ; multus, much, many : spinosns, thorny. 



Diagnosis. Ellipsoidal central body with thin granular endophragm. Archaeo- 

 pyle apical, with zigzag margin. Periphragm forming numerous processes, slender, 

 branched distally. Trabeculae possessing single unconnected acuminate spines. 



PRECINGULAR 

 -PROCESS^ 



POSTCINdULAR 

 PROCESS 



ANTAPICAL 

 PROCESS 



Fig. 56. Adnatosphaeridium vittatum sp. nov. 



