i6j 



MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 



Remarks. The diagnosis of this species has been emended to draw attention to 

 the closed processes, which reflect a definite tabulation characteristic of the genus and 

 the presence of an archaeopyle. The processes were originally considered to be open 

 distally ; however, full re-examination of the holotype at high magnifications has not 

 confirmed this. 



Surculosphaeridium vestitum (Deflandre) 

 PI. 9, fig. 8 ; Text-fig. 42 



1938 

 1938 

 1947 

 1952 

 1955 

 1 960c 



Hystrichosphaeridium vestitum Deflandre 

 Hystrichosphaeridium vestitum Deflandre 

 Hystrichosphaeridium vestitum Deflandre 

 Hystrichosphaeridium vestitum Deflandre 

 Hystrichosphaeridium vestitum Deflandre 



189, pi. 11, figs. 4-6. 

 Deflandre : 688, text-fig. 3. 

 Deflandre, text-fig. 1, no. 3. 

 Deflandre, text-fig. 7. 

 Valensi : 587, pi. 2, fig. 8. 



Baltisphaeridium vestitum (Deflandre) Sarjeant : 397, pi. 13, fig. 8, pi. 14, figs. 13, 14. 



1962a. Baltisphaeridium vestitum (Deflandre) : Sarjeant, pi. 12, figs. 3, 5, 6. 



Remarks. The holotype, from the Oxfordian of France, has been restudied by 

 two of the authors (R.J.D. and W.A.S.S.), through the courtesy of Prof. Deflandre ; 

 and the specimens figured by Sarjeant (1962a) from the Oxfordian of England have 

 also been re-examined in the light of recent studies. The processes of this species are 

 extremely variable in form, so making the elucidation of the reflected tabulation very 

 difficult. The processes are intratabular, the larger ones reflecting one plate of the 

 original dinoflagellate theca, while some of the finer ones, in contrast, occur in twos 

 and threes and represent a larger process which has been subdivided down to the 

 surface of the central body. Thus two or three of these processes may reflect a single 

 plate. The most distinctive and characteristic processes are the ones lying in the 

 cingular zone. These are either deeply furcate or completely divided into two finer 



Fig. 42. Surculosphaeridium vestitum (Deflandre). Position of cingular processes. Left, 

 dorsal view ; right, ventral surface by transparency. V. 51736(1). x c. 650. 



