80 EARLY TERTIARY OSTRACODA 



has a posterodorsal process consisting of two nodes in a vertical row and lacks a 

 lobate eye-tubercle. 



Subgenus ACANTHOCYTHEREIS Howe 1963 

 Type species. Acanthocythereis araneosa Howe 1963. 



Trachyleberis (Acanthocythereis) procapsus sp. nov. 



(Plate 40, figs. 12, 13 ; Plate 41, figs. 1, 3, 4) 



Derivation of name. Latin procapsus, anterior cage ; with reference to the 

 smooth walled area enclosed behind the anterior marginal rim. 



Diagnosis. Acanthocytheris in which a smooth walled area lies behind the anterior 

 marginal rim, anterior and posterior platforms compressed. 



Holotype. Io. 4360, a male carapace (PI. 40, fig. 12 ; PL 41, figs, 1, 3). 



Paratype. Io. 3164. 



Material. Six specimens from the locality below from two horizons (sample 

 nos. 460-j and 460-i) . GSP BM 2598. 



Type locality. Sor Range section. 



Type horizon. Upper Palaeocene, sample no. 460-j. 



Description. Sexual dimorphism apparent ; the males are longer in proportion 

 to the females. Carapace elongate, subrectangular in lateral outline with dorsal and 

 ventral margins almost straight, tapering towards the posterior. Anterior margin 

 broadly rounded, posterior subtriangular. Anterior cardinal angle rounded. Left 

 valve over-reaches the right very slightly at the posterodorsal margin. Greatest 

 height through the anterior cardinal angle and greatest length through the mid- 

 point. In dorsal view the greatest width is situated at the anterior third. Sub- 

 central-tubercle distinct. Eye-tubercle rounded and distinct and lies at the anterior 

 cardinal angle. Surface reticulate (reticulae joined by walls or pustules or papillae). 

 Posterodorsal process consists of small more or less rounded protuberances. Anterior 

 and posterior margins ornamented by a double row of short spines. Anterior and 

 posterior marginal rims high with a smooth walled area behind. Internal details not 

 known. 



Dimensions (mm). 



L H W 



Io. 4360 Carapace male (holotype) o-68 0-32 0-20 



Io. 3164 Carapace female 0-59 0-30 0-20 



Comparison. This species is distinguishable from Trachyleberis (Acanthocythereis) 

 usitata sp. nov. by its deeper reticulation, more elevated marginal rims and spinose 

 anterior and posterior margins. 



The present species has already been compared with Trachyleberis (Acanthocythereis) 

 postcornis sp. nov. and Trachyleberis (Acanthocythereis) decoris sp. nov. 



