MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 



123 



expresses doubt as to which is correct ; he comments on the difficulty of distinguish- 

 ing crests from folds. The tabulation presented in Eisenack's Text-fig. 3 agrees 

 closely with that determined from the English specimens. The plate here designated 

 as postcingular plate 1'" is figured, but not numbered ; Eisenack's plates 1'" to 6'" 

 thus correspond to plates 2'" to 7'" of the scheme here adopted. The presence of 

 anterior and posterior intercalary plates is confirmed. 



Gonyaulacysta orthoceras (Eisenack 1958) is an abundant and characteristic 

 Cretaceous species, having a known range from Upper Valanginian to Turonian. 

 It is clearly distinguishable through its combination of shape, tabulation, and nature 

 of crests : comparisons with other described species are discussed by Eisenack 

 (1958 : 389) and Gorka (1963 : 31). 



Gonyaulacysta aichmetes sp. nov. 

 PL 13, figs. 5. 6 ; Text-fig. 30 



Derivation of name. Greek, aichmetes, spearman, warrior ; referring to the 

 pronounced apical horn. 



Fig. 30. Gonyaulacysta aichmetes sp. nov. Tabulation. Left, ventral view ; 

 right, dorsal view. x c. 1000. 



