56 MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 



hollow, open distally, intratabular, one process per plate area. Number of processes 

 rarely exceeding 30. Archaeopyle apical. 



Type species. Xanthidium tubiferum Ehrenberg 1838. Upper Cretaceous ; 

 Germany. 



Remarks. The central body is composed of two membranes, an inner endo- 

 phragm and an outer periphragm, the latter also comprising the processes. In 

 contrast to the genus Oligosphaeridium, the genus Hystrichosphaeridium posseses 

 6 cingular processes. The cavities of the processes are never in contact with the 

 interior of the central body. The sulcal processes of this genus are often noticeably 

 smaller than the other processes which are approximately of the same size, except 

 for the antapical process which may be larger. 



The above emendation restricts the genus Hystrichosphaeridium to those forms 

 possessing the given tabulation and open processes. Other forms possessing open 

 processes and formerly included in Hystrichosphaeridium have been placed in new 

 genera according to the type of archaeopyle, the tabulation, the number and form 

 of the processes and the shape of the central body. 



Hystrichosphaeridium tubiferum (Ehrenberg) 

 PI. 6, figs. 1, 2 ; PI. 8, fig. 5 ; PI. 10, fig. 2 ; Text-fig. 13 



1838 

 1848 



1854 

 1904 



1933 

 1937 



1940 

 1941 

 1952 

 1963 



Xanthidium tubiferum Ehrenberg, pi. 1, fig. 16. 



Xanthidium tubiferum Ehrenberg ; Bronn : 1375, pi. 1, fig. 16. 



Xanthidium tubiferum Ehrenberg ; Ehrenberg, pi. 7, fig. 48 ; pi. 37, fig. 7, no. 11. 



Ovum hispidium (Xanthidium tubiferum) Ehrenberg ; Lohmann : 21. 



Hystrichosphaera tubifera (Ehrenberg) O. Wetzel : 40, pi. 4, fig. 16. 



Hystrichosphaeridium tubiferum (Ehrenberg) Deflandre : 68. (The specimens figured 



are of H. recurvatum.) 

 Hystrichosphaeridium tubiferum (Ehrenberg) ; Lejeune-Carpentier : 218, figs. 1-4. 

 Hystrichosphaeridium tubiferum (Ehrenberg) ; Conrad, pi. iF, fig. 2F. 

 Hystrichosphaeridium tubiferum (Ehrenberg) ; Gocht, pi. 1, fig. 4. 

 Hystrichosphaeridium tubiferum (Ehrenberg) ; Gorka : 55, pi. 8, figs. 1, 2 ; text-pl. 6, 



figs. 1, 2. 



Emended diagnosis. Central body spherical to subspherical, smooth or slightly 

 granular wall composed of two layers. Processes well developed, tubiform, open 

 distally with entire or serrate circular margin. Processes give a reflected tabulation 

 of 4-5', 6", 6c, 5-6'", ip, 1"" and a variable number of sulcal plates, commonly 4-5. 

 Apical archaeopyle usually present. 



Holotype. Slide XXV in a series of flints from Delitzsch, Institut fur Palaonto- 

 logie u. Museum der Humboldt-Universitat, Berlin. 



Dimensions. Holotype: diameter of central body 33 by 34^, length of processes 

 27-29^, number of processes 24. Paratype : diameter of central body 33 by 36^, 

 length of processes 19-22(1. 



