2oS MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 



Genus ODONTOCHITINA Deflandre 1935a : 234 



Type species. Ceratium (Euceratium) operculatum O. Wetzel 1933. Upper 

 Cretaceous ; Germany. 



Odontochitina operculata (O. Wetzel) 



PL 21, fig. 2 



1933. Ceratium {Euceratium) operculatum O. Wetzel : 170, pi. 11, figs. 21-22. 



I 935- Odontochitina silicorum Deflandre : 234, pi. 10, figs. 8-10. 



1937. Odontochitina silicorum Deflandre ; Deflandre : 47, pi. 18, figs. 8-10. 



1946. Odontochitina operculata (O. Wetzel) Deflandre, cards 1016-19. 



1948. Palaeoceratium operculatum (O. Wetzel) O. Wetzel : ?342. 



1950. Dreihornige Hullen mit Stachelkleid, O. Wetzel : 170, pi. 13, fig. 6. 



1952. Odontochitina operculatum (O. Wetzel) ; Firtion : 160, pi. 8, fig. 9. 



1955. Odontochitina operculata (O. Wetzel) ; Deflandre & Cookson : 291, pi. 3, figs. 5, 6. 



1955. Odontochitina operculata (O. Wetzel) ; Deflandre-Rigaud : 19. 



1955. Odontochitina operculata (O. Wetzel) ; Valensi : 594, pi. 4, fig. 7. 



1958. Odontochitina operculata (O. Wetzel) ; Eisenack : 393, pi. 27, figs. 7, 8. 



J 959- Odontochitina operculata (O. Wetzel) ; Gocht : 64, pi. 6, fig. 12. 



1 961. Odontochitina operculata (O. Wetzel) ; Alberti : 30, pi. 6, figs. 6-9. 



1961. Odontochitina operculata (O. Wetzel) ; Eisenack : 323, pi. 36, fig. 3. 



1962. Odontochitina silicorum Deflandre ; Pocock : 78, pi. 14, figs. 211, 212. 



1963. Odontochitina operculata (O. Wetzel) ; Gorka : 35, pi. 4, figs. 1-5. 



1963. Odontochitina operculata (O. Wetzel) ; Baltes : 584, pi. 5, figs. 1-4. 



1964. Odontochitina operculato (O. Wetzel) ; Singh : 147, pi. 20, figs. 9, 10. 



Remarks. This species is long-ranging and widespread : it has been recorded 

 from the Upper Jurassic of Canada by Pocock (1962) and has a well-documented 

 range in the Cretaceous, from Upper Hauterivian to Campanian. It is present in low 

 numbers in the assemblages from 19-25 metres depth in the Shell West Heslerton 

 Borehole (Upper Barremian). All specimens seen lacked the apex ; the figured 

 specimen, B.M.(N.H.) slide ¥.51730(4), is the best-preserved, having an overall 

 length of 133-5^, breadth 88[x, the central body being 53^ long and 48^ broad, the 

 lateral horn c.55[jl long and the antapical horn 83'5fx long. The range in dimensions 

 observed was overall lengths 120-133- 5[x, breadths 67-100(0. : these fall well within 

 the previously quoted ranges. Detached horns, probably of 0. operculata, were also 

 observed. 



Odontochitina operculata is also present at all levels in the Cenomanian of the H.M. 

 Geological Survey Borehole at Fetcham Mill, Surrey. 



Genus FROMEA Cookson & Eisenack 1958 : 55 



Type species. Fromea amphora Cookson & Eisenack 1958. Cretaceous (Aptian 

 to Cenomanian) ; Australia. 



