MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 195 



exceeds 1 to 1. The slender, simple or branched processes are hollow, open distally 

 with an aculeate margin, the aculei being patulate, orthogonal or even recurved. 

 The processes reflect a tabulation agreeing with that of the type species W. articulata. 

 The processes become shorter towards the horns. The periphragm can be up to 

 i/2[x thick, and it is always smooth. 



The capsule is ovoidal or subcircular in outline, ellipsoidal in cross section. It lies 

 at a variable distance from the inner surface of the periphragm, and has a wall up to 

 2[x thick, which may be smooth or granular. Commonly observed in specimens of 

 Wetzeliella (W.) similis is a local thickening of the endophragm directly opposite the 

 point of origin of the horns. The significance of this may be that the horns are 

 points of weakness within the cyst. 



Dimensions. Outer Shell, length ioo-i58[jl, breadth 117-166^. Capsule, length 

 65-97 -5[x, breadth 66-g2\i. Length of processes 8-i8[x. Number of specimens 

 measured, 15. 



Occurrence. Whitecliff and Enborne. 



Stratigraphic range. Oligocene of Germany (Eisenack 1954) and the London 

 Clay. 



Wetzeliella (Wetzeliella) solida (Gocht) comb. nov. 



1955 Dracodinium solidum Gocht (pars) : 88-91, text-figs. 3a, b, 4a, b, 5a. 

 1 961 Wetzeliella {Dracodinium) Solida (Gocht) Eisenack : 306. 



Discussion. Only a few specimens of W. Solida have been recorded from the 

 London Clay. They are characterised by the absence of an apical horn. The 

 surface of the periphragm bear slender, simple or branched processes that distally 

 have an aculeate margin. The processes on the ambitus of the periphragm are often 

 the shortest. The archeopyle is intercalary, the tabulation is the same as in other 

 species of Wetzeliella with the apicals being reduced in size. 



Gocht (1955) erected the genus Dracodinium on the single species D. solidum and 

 distinguished it from Wetzeliella on the absence of an apical horn. Within the 

 species D. solidum he unfortunately included two distinct forms, those with inter- 

 calary archeopyles and others with an apical archeopyle. Since the emended 

 diagnosis of Wetzeliella excludes forms with an apical archeopyle, Gocht 's latter type 

 needs transferring to a new genus, whilst the forms with the intercalary archeopyle 

 are included within the genus Wetzeliella as W. solida. 



Dimensions. Periphragm, length io5-ii7(x, breadth 117 -5-137 y.. Capsule, 

 length 68— 76^, breadth 69-82^. Number of specimens measured, 5. 



Occurrence. Whitecliff and Enborne. 



Stratigraphic range. W. solida has previously been recorded from the Eocene 

 or Oligocene? of Germany (Gocht 1955). The forms classed as Dracodinium Solidum 

 by Alberti (1961, pi. 1, fig. 9) appear to be another as yet unnamed species. 



