14 APPENDIX TO "STUDIES ON MESOZOIC 



ringing the antapex may be longer than the others), or may be relatively constant. 

 The spines may be simple or may bifurcate or ramify near the tips : their length is 

 constantly less than £ of the longest shell cross-measurement. A precingular 

 single-plate archaeopyle, formed by loss of plate 3", is developed. Surface of peri- 

 phragm smooth, granular or punctate. Forms with a nodose or reticulate surface 

 have not, to date, been encountered : those with a general spine cover are excluded. 



Type species. Hystrichogonyaulax cornigera (Valensi) Sarjeant, comb. 



nov., =Gonyaulax cornigemm (sic) Valensi, 1953 ; 27, pi. 1 figs. 4, 8, 10, pi. 2 



figs. 1-2, pi. 13 fig. 5, text-fig. 2a. Middle Jurassic (Upper Bathonian), France. 

 Other Species. Hystrichogonyaulax nealei (Sarjeant) Sarjeant, comb, nov., 



= Gonyaulax nealei Sarjeant, 1962 ; 480-1, pi. 69 fig. 1, text-fig. 2. Upper 



Jurassic, England. 

 Remarks. This new genus corresponds to Leptodinium in its general morphology, 

 differing in the possession of long sutural spines instead of low crests. It is most 

 abundant in the Middle Jurassic and is characteristically numerous in Northwest 

 European Bathonian sediments : the total known range is Middle to lower Upper 

 Jurassic. On morphological grounds, it might be visualized as possibly ancestral to 

 the genus Gonyaulacysta (which includes the species G. cladophora, with similar 

 sutural spines but with an apical horn) and to the genus Leptodinium, by loss of the 

 sutural spines ; at present, however, this must be regarded as a speculation only. 



Other generic reallocations 



Dichadogonyaulax pannea (Norris) Sarjeant, comb, nov., = Leptodinium panneum 



Norris, 1965 ; 796-8, figs. 3, 10-13. Upper Jurassic, England. 

 Dichadogonyaulax schizoblata (Norris) Sarjeant, comb, nov., ^Leptodinium 



schizoblatum Norris, 1965 ; 798-800, figs. 4-5, 14-17. Upper Jurassic, 



England. 

 }Litosphaeridium striatoconus (Deflandre & Cookson) Sarjeant, comb, nov., 



=Hystrichosphaeridium striatoconus Deflandre & Cookson, 1955 ; 275-6, 



pi. 2, fig. 10, text-fig. 36 (Transferred to Baltisphaeridium by Downie & Sarjeant 



1963 ; 92). Upper Cretaceous, Australia. 

 Meiourogonyaulax bulloidea (Cookson & Eisenack) Sarjeant, comb, nov., 



= Gonyaulax bulloidea Cookson & Eisenack, 1960b ; 247, pi. 37 fig. n text-fig. 



4. Upper Jurassic, Western Australia. 

 Meiourogonyaulax caytonensis (Sarjeant) Sarjeant, comb, nov., =Gonyaulax 



caytonensis Sarjeant, 1959 ; 330-2, pi. 13 fig. 1, text-fig. 1. Middle Jurassic, 



England. 

 ? Meiourogonyaulax cristulata (Sarjeant) Sarjeant, comb, nov., —Gonyaulax 



cristulata Sarjeant, 1959 ; 332-4, pi. 13 fig. 2, text-fig. 2. Middle Jurassic, 



England. 

 Meiourogonyaulax decapitata (W. Wetzel) Sarjeant, comb, nov., =Gonyaulax 



decapilata W. Wetzel, 1966 ; 869, pi. 16 figs 7a-b. Middle Jurassic, Germany. 



