50 EARLY TERTIARY OSTRACODA 



Diagnosis. A species of Occultocythereis in which surface is ornamented with 

 largish puncta. Posteroventral margin rounded, posteroventral process a short 

 slightly oblique ridge well-developed in female, ill-defined in male, anteroventral 

 swelling small. 



Holotype. Io. 4342, a female carapace (PI. 25, figs. 6, 7, 10, 11). 



Paratype. Io. 4288. 



Material. Four specimens from the locality below from three horizons (sample 

 nos. 3173, 3174 and 3177). GSP BM 2558-9. 



Type locality. Rakhi Nala section. 



Type horizon. Green and Nodular Shales, sample no. 3177. 



Description. Dimorphic ; the females are higher and wider than the males. 

 Carapace subrectangular in lateral view with greatest length in the middle and 

 greatest height in the anterior third. Anterior margin broadly rounded, postero- 

 dorsal slope very slightly concave, posteroventral margin rounded, dorsal and ventral 

 margins almost straight, very slightly converging towards the posterior. Anterior 

 cardinal angle rounded, posterior cardinal angle distinct about no . Valves almost 

 equal. In dorsal view the greatest width lies in the posterior third. Eye-tubercle 

 more or less distinct. Subcentral-tubercle present but not pronounced with a small 

 swelling below and slightly anterior to it. Surface ornamented by large puncta. The 

 posterodorsal process is a short projecting ridge extending vertically towards the 

 mid-line but not reaching it. It extends anteriorly in a short dorsal ridge termina- 

 ting in the anterior third of the dorsal margin. The posteroventral process is a short 

 slightly oblique ridge lying in the posteroventral swelling. In the male dimorph 

 the posteroventral swelling is less well-developed and the posteroventral ridge ill- 

 defined. Anterior marginal rim prominent, ventral and posterior marginal rims less 

 prominent. Anterior marginal area ornamented by numerous, short ridges lying 

 between the rim and the margin. Posteroventral margin decorated by four to five 

 short spines. 



Dimensions (mm). 



L H w 



Io. 4288 Carapace male 0-38 0-21 0-13 



Io. 4342 Carapace female (holotype) 0-38 0-22 0-16 



Comparison. Occultocythereis peristicta sp. nov. Morphotype C is larger, has a 

 vertical rather than an oblique posteroventral ridge joining the second posterior 

 tubercle and the ventral ridge. Further, it lacks the dorsal ridge and the short 

 ridges between the anterior rim and the anterior margin. 



Occultocythereis peristicta sp. nov. 

 (Plate 25, figs. 13-17 ; Plate 26 ; Plate 27, figs. 1-2) 



Derivation of name. Greek peristiktos, punctate or dappled. 



Diagnosis. A punctate group of morphotypes of the genus Occultocythereis with- 



