MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 145 



Meiourogonyaulax valensii sp. nov. 

 PL 15, %• 7 ; Text-fig. 37 



1953. Gonyaulax sp. indet., Valensi : 27, pi. 2, figs. 12, 13. 



Derivation of name. Named after Lionel Valensi, who published the first full 

 descriptions of Middle Jurassic dinoflagellate/acritarch assemblages. 



Diagnosis. A Meiourogonyaulax having a broadly ellipsoidal theca ; lacking 

 apex in all specimens seen. Tabulation ?4', oa, 6", 6c, 6'", ip, 1 p. v., 1"". Crests of 

 moderate height, slightly striated and irregularly perforate, with smooth or finely 

 denticulate distal edges. Spines present at some crest nodes. Cingulum strongly 

 spiral, relatively broad ; sulcus broadening posteriorly, subdivided by low ridges. 

 Shell surface punctate or alveolar. 



Holotype. Specimen B.S.60 (L. Valensi preparation), Laboratoire de Micro- 

 paleontologie, Ecole Pratique des Hautes Etudes, Paris. Chert from Airvault, 

 Poitou, France. Middle Jurassic (Bathonian). 



Dimensions. Holotype : overall length 70^, breadth 70^1 ; shell length, approx. 

 6o[jl, breadth approx. 50(1 ; width of transverse furrow c.6[x. 



Description. Although this species is based on Valensi's single specimen, the 

 author has also seen a number of specimens in material from the Bathonian of the 

 Aquitaine Basin, unfortunately not available for description. 



Fig. 37. Meiourogonyaulax valensii sp. nov. Tabulation. Left, ventral view 

 right, dorsal view. X c. 1000. 



