MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 



137 



Psaligonyaulax deflandrei sp. nov. 

 PL 14, figs. 7, 8 ; Text-fig. 35 



1964. Gonyaulax cassidata Eisenack & Cookson ; Cookson & Hughes : 42, pi. 5, fig. 11 only. 



Derivation of name. Named in honour of Professor Georges Deflandre, who has 

 published fundamental studies of dinoflagellates in the French Upper Cretaceous 

 between 1932 and the present. 



Diagnosis. A Psaligonyaulax having a spindle-shaped outline, truncated 

 posteriorly, with ovoidal inner body. Apical pericoel surmounted by bifid horn, 

 antapical pericoel flattened. Tabulation 4', ia, 6", 6c, 6'", ip, 1"". Crests of moder- 

 ate height with smooth or denticulate edges. Cingulum broad, strongly spiral : 

 sulcus narrower but widening posteriorly. Surfaces of endophragm and periphragm 

 smooth or only minutely granular : an irregular scatter of tubercles may be present 

 on periphragm. 



Holotype. Geol. Surv. Colin, slide PF.3049(i). Chalk, H.M. Geological Survey 

 Borehole, Fetcham Mill, Surrey, at 730 feet depth. Upper Cretaceous (Cenomanian) . 



Dimensions. Holotype : overall length 75[x, breadth 44^ ; length of inner body 

 35 \i, breadth 40[x. Range of dimensions : overall lengths 72 to 82 ;x, breadths 43 to 

 6o[x. 



Fig. 35. Psaligonyaulax deflandrei sp. nov. Tabulation. Left, ventral view ; 

 right, dorsal view (plate 3" is missing). x c. 1000. 



