MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 207 



Holotype. B.M.(N.H.) slide ^^.51723(3). Speeton Clay, Shell West Heslerton 

 Borehole, West Heslerton, Yorks., at 42-5 metres depth. Lower Cretaceous (Lower 

 Barremian) . 



Dimensions. Holotype — overall length io5[x, breadth ii8[jl ; shell length iijjl, 

 breadth io2[x ; spines c.jy. long. Range of dimensions : overall lengths c.i20-i45(x, 

 breadths c.io5-i30fx. 



Description. This species is moderately abundant, some 25 specimens having 

 been encountered ; complete shells were infrequent, detached apices and shells 

 lacking an apex being commoner. 



The shell is approximately club-shaped : its asymmetry is so pronounced that a 

 longitudinal division would leave some 60% on one side, some 40% on the other. 

 The epitract slopes smoothly into the apical horn ; the hypotract is surmounted by an 

 antapical bulge of small height and larger amplitude. The surface is very minutely 

 granular. 



There is a dense cover of short spines, most often capitate, less frequently evexate, 

 oblate, bifid or bifurcate : these sometimes suggest arrangement into lines, but no 

 coherent pattern was determined. An equatorial belt of moderate breadth, corres- 

 ponding to the cingulum, lacks spines : a sulcus is not distinguishable. 



The holotype shows fission to form an archaeopyle, which has however, not 

 become detached. Its margin is distinctly angular, suggesting a tabulation pattern 

 not otherwise indicated. 



Remarks. In its combination of shape, process cover and mode of archaeopyle 

 formation, Doidyx anaphrissa sp. nov. differs from all other described species. 



Genus BROOMEA Cookson & Eisenack 1958 : 41 



Type species. B. ramosa Cookson & Eisenack 1958. Middle-Upper Jurassic ; 

 Australia. 



}Broomea longicornuta Alberti 

 PL 21, fig. 1 



1961. IBroomea longicornuta Alberti : 27, pi. 5, figs. 18-21, pi. 6, figs. 1, 2. 



Remarks. This species, originally described from the Lower Cretaceous (Hauteri- 

 vian-Upper Barremian) of Germany, is represented by a single specimen in the 

 assemblage from the Speeton Clay of the West Heslerton Borehole at 19- 25 metres 

 depth (Upper Barremian). The dimensions of this specimen, B.M.(N.H.) slide 

 V. 51733(1), are overall length c.285^ ; shell length ioofj., breadth 480. ; length of 

 apical horn c.i30[x ; length of unbent antapical horn 55^. This falls within the 

 range of overall lengths quoted by Alberti (248-298^). 



