AND CAINOZOIC DINOFLAGELL ATE CYSTS " 13 



Leptodinium maculatum Cookson & Eisenack, 1961 ; 40, pi. 2 figs. 5-6. PUpper 



Eocene, Rottnest Island, Australia. 

 Leptodinium margaritiferum (Cookson & Eisenack) Sarjeant, comb. nov. 



=Gonyaulax margaritifera Cookson & Eisenack, 1960a ; 5-6, pi. 2 figs. 1-2 



text-fig. 1. Upper Cretaceous, Western Australia. 

 Leptodinium membranigerum Gerlach, 1961 ; 162-165, pi. 26 figs. 1-4, 7 



text-figs 4,5. Oligocene-Miocene, Germany. 

 Leptodinium millioudi (Sarjeant) Sarjeant, comb, nov., =Gonyaulax millioudi 



Sarjeant, 1963b ; 86-88, pi. 1 figs. 4-7. Upper Jurassic, Switzerland. 

 Leptodinium mirabile Element, i960 ; 48-50, pi. 6 figs. 7-10, text-fig. 25-7 



Upper Jurassic, Germany. 

 }Leptodinium mosaicum (Downie) Sarjeant, comb, nov., =Palaeoperidinium 



mosaicum Downie, 1957 ; 424, pi. 20 fig. 7, text-fig. 2f. (Transfer of this 



species to Gonyaulacysta was proposed, as a provisional measure, by Sarjeant 



1967 ; 253). Upper Jurassic, England. 

 Leptodinium paradoxum Wall, 1967 ; 106-7, pi- T 5 fig s - 5 _ 8, text-figs. 2, 3A, 3B. 



Miocene — Recent, Yucatan Basin, Caribbean Sea. 

 }Leptodinium pilum (Gocht) Sarjeant, comb, nov., =Palaeoperidinium pilum 



Gocht, 1959 ; 56-7, pi. 6 fig. 14, pi. 8 fig. 8. (Transfer of this species to Gony- 

 aulacysta was proposed, as a provisional measure, by Sarjeant, 1967 ; 255). 



Lower Cretaceous, Germany. 

 Leptodinium porosum (Lejeune-Carpentier) Sarjeant, comb, nov., =Gonyaulax 



porosa Lejeune-Carpentier, 1946 ; 193. 196, text-fig. 6. Upper Cretaceous, 



Belgium. 

 Leptodinium sphaericum Wall, 1967 ; 108, pi. 15 figs. 11-15, text-fig. 2a-c. 



Pleistocene — Recent, Yucatan Basin, Caribbean Sea. 

 Leptodinium strialatum Wall, 1967 ; 107-8, pi. 15 figs. 9-10, text-fig. 5. 



Miocene — Recent, Yucatan Basin, Caribbean Sea. 

 Leptodinium striatum (Clarke & Verdier) Sarjeant, comb, nov., = Gonyaulacysta 



striata Clarke and Verdier, 1967 ; 31-32, pi. 4 figs. 11-13, pi. 5 fig. 15, text-fig. 



12. Upper Cretaceous, England. 



Genus HYSTRICHOGONYA ULAX gen. nov. 



Derivation of name. In reference to the Gonyaulax-type tabulation exhibited, 

 and to the presence of spines on the sutures. 



Diagnosis. Proximate dinoflagellate cysts, spheroidal, ovoidal, ellipsoidal or 

 polyhedral, with the reflected tabulation 3-4', o-ia, 6", 6c, 5-6'", ip, 0-1 p.v., 

 1"", o-x s. Apical, median and antapical horns lacking. Cingulum strongly or 

 weakly helicoid, laevorotatory ; cingular plates well or poorly marked. Sulcus 

 generally but not constantly extending onto the epitract, undivided or subdivided 

 into a variable number of small plates. Rarely, an apical or an antapical pericoel 

 may be present (but not both) ; the two shell layers are otherwise in continuous 

 contact. Sutures marked by lines or low ridges from which arise isolated spines ; 

 the length of spines may vary according to position on the test (e.g. the spines 



