g6 MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 



Remarks. The genus Diphyes is here restricted to include forms possessing two 

 types of processes — numerous fine ones and a single large antapical. D. nudum 

 Cookson does not possess any processes at all and certainly does not belong in this 

 genus. 



Diphyes colligerum (Deflandre & Cookson) 

 PL 4, figs. 2, 3 



1953 

 1955 

 1962 



fig 

 1963 

 1965 



Hystrichosphaeridium sp. C. Cookson : 115, pi. 2, figs. 29, 30. 

 Hystrichosphaeridium colligerum Deflandre & Cookson : 278, pi. 7, fig. 3. 

 Hystrichosphaeridium colligerum Deflandre & Cookson ; Cookson & Eisenack : 44, pi. 



9- 



Baltisphaeridium colligerum (Deflandre & Cookson) Downie & Sarjeant : 91. 

 Diphyes colligerum (Deflandre & Cookson) Cookson : 86, pi. 9, figs. 1-12. 



Emended diagnosis. Ovoidal to spherical central body with wall composed of 

 thin endophragm and outer finely reticulate periphragm. Processes composed of 

 periphragm, numerous, simple, hollow, open or closed distally. One single broad 

 antapical process. Total number of processes exceeding 50. 



Holotype. P.16301, National Museum of Victoria, Australia. Princetown 

 Member of Dilwyn Clay, Lower Eocene ; Point Ronald, Vic. Dept. of Mines bore, 

 Victoria. 



Material (Figured). B.M.(N.H.) slide V.5i754(i). 157 feet above base of 

 London Clay ; Whitecliff Bay, Isle of Wight. 



Dimensions. Holotype : diameter of central body 33[x, overall diameter 56^, 

 length of antapical process 20[x, width of antapical process 13(1, length of small 

 processes approx. I3fx. Range : diameter of central body 30-33(1., overall diameter 

 56— 59(x, length of small processes approx. 13^. Figured specimens diameter of 

 central body 33 by 37 - 5(Jt, length of antapical process i6(jl, width of antapical process 

 i5jx, length of small processes n-i5[x. Range of English specimens : diameter of 

 central body 29-41^, length of antapical process i6-2ifx, width of antapical process 

 8-i5[x, length of small processes 8-i5(x. 



Description. An apical archaeopyle and the large antapical process enable 

 easy orientation of specimens of this species. The antapical process is hollow, 

 cylindro-conical, occasionally closed, and bears small tubules, 2-3^ long, towards the 

 distal extremity. The tubules can take the form of simple conical protuberances or 

 can have slightly bifurcate extremities. The smaller processes are commonly 

 simple, occasionally united proximally, and may be open or closed distally. They 

 are slender but do vary in width, and in specimens possessing open processes they 

 taper to a distal neck before terminating with a sightly expanded opening. The 

 distal margin may be finely serrate or entire. Both types of processes are slightly 

 fibrous and do not communicate with the interior of the central body. There are 

 commonly 4, regularly distributed, processes for each precingular plate area ; 2-4 

 for the postcingular plate areas and a constant 2 in the cingular plate areas. 



