MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 203 



Muderongia staurota sp. nov. 

 PL 21, figs. 6, 7 ; PL 23, fig. 4 ; Text-fig. 53 



Derivation of name. Greek, staurotos, cruciform. 



Diagnosis. A Muderongia having an ovoidal to ellipsoidal enclosing body, 

 prolonged into four strong horns. Apical horn strong and tapering, length slightly 

 less than length of shell alone. Lateral horns quite short, less than shell breadth, 

 at first almost parallel sided, but at about one-third length, anterior margin tapering 

 backward to form an angle with posterior margin. Antapical horn basically conical, 

 with slight out-bulge at one side ; length also less than length of shell alone. Inner 

 body ovoidal to ellipsoidal. Periphragm smooth or finely pitted ; endophragm 

 varying from smooth to densely granular. Shell showing neither trace of tabulation 

 nor of cingulum or sulcus. An apical archaeopyle is formed. 



Holotype. B.M.(N.H.) slide ¥.51724(3). Speeton Clay, Shell West Heslerton 

 Borehole at 42-50 metres depth, West Heslerton, Yorkshire. Lower Cretaceous 

 (Lower Barremian). 



Paratype. B.M.(N.LL) slide ¥.51718(3). Same locality and horizon. 



Fig. 53. Muderongia staurota sp. nov. Left, holotype. Right, paratype. The variation 

 in proportions and in degree of granularity of the inner body is shown : the holotype 

 shows incipient formation of an archaeopyle. x c. 500. 



