28 EARLY TERTIARY OSTRACODA 



appears to be drawn upside down, shows longitudinal ridges continuing in the 

 anterior part of the carapace. 



Remarks. Cythere costellata (Roemer) is now regarded as a species of the genus 

 Cytheretta. Because of the imperfect preservation, it has not been possible to observe 

 whether the present species has any eye-tubercles. 



Buntonia Sp.A 

 (Plate 13, figs. 6, 7, 9) 



Figured specimen. Io. 3114. 



Material. Two specimens from the locality and horizon below. 



Locality. Rakhi Nala section. 



Horizon. Lower Rakhi Gaj Shales, sample no. 3133. 



Description. Carapace small, almost triangular in lateral outline. Greatest 

 length lies below mid-point, greatest height in anterior third. In dorsal view the 

 carapace is widest just posterior to the middle and tapers towards anterior and 

 posterior ends ; posterior pointed. Anterior end broadly and obliquely rounded, 

 posterior narrow and somewhat rounded ; dorsal and ventral margins taper towards 

 the posterior. Anterior cardinal angle rounded and well-developed. Left valve 

 larger than right valve. Surface ornamented with some ten longitudinal ridges. 



Dimensions (mm). 



L H w 



Io. 3114 Carapace 0-50 0-27 0-32 



Comparison. Buntonia devexa sp. nov. (PI 13, figs. 1-5) is much larger, has a less 

 triangular carapace with a gentle slope on the dorsal margin. Further, B. devexa has 

 a rounded rather than pointed posterior in dorsal view and has longitudinal ridges 

 which do not continue towards the anterior. 



Genus COSTA Neviani 1928 



Diagnosis. Trachyleberididae in which ornamentation is dominated by three or 

 four longitudinal ridges, the median or second ridge running back from the sub- 

 central-tubercle towards posterodorsal corner in anterior two-thirds of length, then 

 curving sharply down towards posteroventral corner in posterior third of length. 



Type species. Cytherina edwardsii Roemer 1838. 



Subgenus COSTA sensu stricto 

 Diagnosis. Costa with three longitudinal ridges. 



Subgenus PARACOSTA nov. 



Derivation of name. Greek para, near ; with reference to the strong resem- 

 blance to the subgenus Costa. 



