MESOZOIC AND CAINOZOIC DINOFL AGELLATE CYSTS 



187 



Wetzeliella (Wetzeliella) reticulata sp. no v. 



PI. 19, figs. 3, 6 ; Text-fig. 48 



Derivation of Name. Latin, reticulatus, netted, net-like. 



Diagnosis. Periphragm with distinctive pentagonal outline, produced into 

 horns at each angle ; one apical, two lateral and two antapical horns. Right 

 antapical always larger than left antapical horn. Periphragm totally enclosing 

 ovoidal capsule. Surface of periphragm bearing intratabular processes, usually 

 restricted to simulate complexes ; processes lying immediately within boundaries of 

 plates. Processes diversely united within each complex by series of trabeculae, 

 giving a reticulum extending over plate and assuming plate outline. Processes of 

 adjacent plates not unified. Reflected tabulation 4', 3a, 7", 5c, 5'", 2"", 3 or 4s. 

 Archaeopyle present. 



Holotype. B.M.(N.H.) slide ¥.51752(6). London Clay ; Sheppey, Kent, 

 sample 2. 



Dimensions. Holotype : periphragm length 146^, breadth 162- 5[x, capsule 

 length io6[x, breadth iiojj.. Observed range : outer shell length 146-167^, breadth 

 150-162- 5[x. Capsule length i03-io6jx, breadth 95-1 iopi. Number of specimens 

 measured, 2. 



Description. The shape and size of the plates of the periphragm of W. reticulata 

 agree with those of W. coleothrypta (see previous description). The hollow, closed, 

 cylindrical processes, in connection with the pericoel cavity are distally divided into 

 numerous secae which ramify and are united by means of trabeculae with secae from 

 processes of the same plate. The boundary of the reticulum thus formed is extremely 

 regular, unconnected spines branching off only infrequently. Each reticulum 

 mirrors the shape of the plate it overlies and is only slightly smaller. The trabeculae 

 of the reticulum are taeniate. 



Fig. 48. Wetzeliella {Wetzeliella) reticulata sp. nov. Left, tabulation of the ventral (lower) 

 surface of holotype ; right, tabulation of the dorsal (upper) surface. Stippling denotes area of 

 simulate process complexes. The archaeopyle in the endophragm resulting from loss of plate 

 2a is shaded. 



