FROM WEST PAKISTAN 49 



the anteroventral corner. Anteromedian swelling well-developed. A marginal rim 

 extends around the anterior, ventral and posterior margins, elevated on the anterior 

 margin but less elevated around the venter and posterior. Small ridges run be- 

 tween the anterior marginal rim and the anterior margin (these are better seen in 

 ventral view). Four to five short spines ornament the posteroventral margin. 

 Internal details not known. 



Dimensions (mm.) 



L H w 



Io. 4287 Carapace male 0-39 0-18 o-n 



Io. 4339 Carapace female (holotype) 0-38 0-20 0-13 



Comparison. Occultocythereis indistincta sp. nov. is much larger, has a continuous 

 rather than a broken dorsal ridge and lacks the oblique posterior ridge which joins 

 the posterodorsal process and the ventral ridge. 



Remarks. 0. interrupta is so far only known from the Upper Palaeocene of the 

 Sor Range section. 



Occultocythereis Sp.A 

 (Plate 25, figs. 1, 2, 5, 12) 



Figured specimen. Io. 3136. 



Material. Only one specimen from the locality and horizon below. 



Locality. Rakhi Nala section. 



Horizon. Lower Rakhi Gaj Shales, sample no. 3672. 



Description. Carapace subrectangular with ventral inflation. Dorsal and 

 ventral margins almost straight, tapering towards the posterior ; anterior margin 

 broadly and obliquely rounded, posterior narrowly rounded with a slight concavity 

 in the posterodorsal corner. Greatest length runs through the middle, greatest 

 height in the anterior two-fifths and greatest width in the posterior third. Anterior 

 and posterior cardinal angles rounded. Valves almost equal. Eye-tubercle distinct 

 but low. Subcentral-tubercle weak. Surface reticulate. Posterodorsal process 

 consists of a more or less rounded tubercle which extends anteriorly in a weak dorsal 

 ridge. Anterior marginal rim well-marked, ventral and posterior marginal rims less 

 elevated. Posterior ornamented with 4-5 short spines. 



Dimensions (mm). 



L H w 



Io. 3136 Carapace 0-42 0-22 0-17 



Remarks. This species differs from other known species of the genus Occulto- 

 cythereis in its obliquely rounded anterior margin. 



Occultocythereis spilota sp. nov. 

 (Plate 25, figs. 3, 4, 6-11) 



Derivation of name. Greek spilotos, spotted ; with reference to the largish 

 puncta. 



