16 EARLY TERTIARY OSTRACODA 



Alocopocy there rupina sp. nov. 

 (Plate 2, figs. 5, 8-10 ; Plate 3, figs. 1-4) 



Derivation of name. Latin, rupina, " chasm " ; with reference to the antero- 

 dorsal furrow and associated ridges. 



Diagnosis. Alocopocythere in which anterodorsal furrow is delimited anteriorly 

 by a short almost vertical ridge and posteriorly by the anterior part of the dorsal 

 ridge. Surface reticulate with seven longitudinal ridges. Anterior and posterior 

 plains almost smooth. 



Holotype. Io. 4314, a male carapace (PI. 2, figs. 5, 8-10). 



Paratype. Io. 4262. 



Material. 41 specimens from the locality below from one horizon (sample no. 

 3111). GSP BM 2509-10. 



Type locality. Rakhi Nala section. 



Type horizon. Gorge Beds, sample no. 3111. 



Description. Sexual dimorphism strong, the males are longer than the females. 

 Carapace subrectangular in lateral view. Dorsal margin sinuous, ventral margin 

 slightly concave in front of the middle, anterior margin broadly rounded, posterior 

 narrowly rounded. Anterior cardinal angle protruding particularly in right valve, 

 posterior cardinal angle less well-developed. Left valve slightly over-reaches right 

 valve at anterior cardinal angle and in the region of posterodorsal corner. Eye- 

 tubercle rounded and distinct. Subcentral-tubercle well-developed. Surface orna- 

 mentation with seven longitudinal ridges ; the dorsal ridge begins above and very 

 slightly to the anterior of the subcentral-tubercle and is convex in the middle 

 culminating in the posterior quarter. The four ridges below the dorsal ridge are 

 almost confined posterior to the subcentral-tubercle, the second ridge from the centre 

 is the longest and is slightly curved ; it commences above the anteroventral corner 

 and slopes obliquely upwards towards the posterior ending in the posterior quarter. 

 The ventral ridge is confined in the posterior part of the carapace and is intercalated 

 between the ventral margin and the second ventral ridge, to which it is almost 

 parallel. Anterodorsal furrow well-developed, delimited on the anterior by a short 

 almost vertical ridge, and on the posterior by the anterior portion of the dorsal ridge. 

 Anterior and posterior platforms almost smooth, compressed. Anterior marginal 

 rim elevated, ventral and posterior marginal rims less high. Radial pore canals not 

 detectable. Duplicature moderate. Selvage well-marked ; it is submarginal in left 

 valve but in the outer third of the duplicature in right valve, which also has well- 

 developed anterior and ventral flange grooves. Hinge holamphidont with stirpate 

 anterior tooth in right valve. 



Dimensions (mm). 



L H w 



Io. 4314 Carapace male (holotype) o-68 0-37 0-34 



Io. 4262 Carapace female 0-59 0-37 0-34 



Comparison. A. rupina can easily be differentiated from other known species of 



