4° 



EARLY TERTIARY OSTRACODA 



in a vertical row of four adductors and a U-shaped frontal scar opening towards the 

 anterodorsal corner. Hinge holamphidont : 



Left valve 



Rounded socket, confluent 



with ocular sinus, seen 



in a few specimens. 



Subcorneal tooth which has Deep rounded socket 



straight anterior but convex opening into postero- 



Element 

 Anterior 



Anteromedian 



Right valve 

 Projecting stirpate 

 tooth. 



Posteromedian 

 Posterior 



Dimensions (mm). 



posterior in dorsal view. 

 Denticulate bar. 

 Deep, slightly elongate 

 socket. 



median groove. 

 Locellate groove. 

 Pessular tooth, but sub- 

 rectangular in lateral view. 



L 



H 



o-8i 



0-49 



o-8 3 



0-49 



078 



0-49 



076 



0-46 



071 



0-44 



071 



0-44 



077 



0-46 



072 



0-44 



079 



0-44 



w 



0-46 



Io. 3125 Left valve male 



Io. 3127 Right valve male 



Io. 4331 Carapace female (holotype) 



Io. 3126 Left valve male 



Io. 3124 Right valve female 



Io. 3128 Right valve female 



Io. 4280 Left valve male 



Io. 3120 Right valve female 



Io. 3122 Right valve male 

 Comparison. This species resembles Gyrocythere perfecta sp. nov. (PI. 22, figs. 1-10) 

 but differs from it in being larger and having more prominent longitudinal ridges and 

 an eye-tubercle. Moreover, the subcentral tubercle in G. exaggerate/, is distinctly 

 bilobate. 



Remarks. The occurrence of this species ranges through 390 ft. in the Zao River 

 section and 15 ft. in the Rakhi Nala section. It seems likely that it will prove a 

 useful horizon marker. 



Gyrocythere parvicarinata sp. nov. 

 (Plate 20, figs. 1-4, 6-8, 12) 



Derivation of name. Latin parvus, little + carinatus, ridged; with reference to 

 the longitudinal ridges. 



Diagnosis. A strongly reticulate species of the genus Gyrocythere with three 

 longitudinal ridges, median ridge ill-defined, posterior subtriangular, eye-tubercle 

 distinct, subcentral-tubercle well-developed. 



Holotype. Io. 4334, a male carapace (PI. 20, figs. 1, 2, 6, 7). 



Paratype. Io. 4281. 



Material. Over 100 specimens from the Rakhi Nala section from 25 horizons 

 (sample nos. 3153, 3168 to 3172, 3179, 3180, 3185, 3192, 3193, 3199, 3200, 3401 to 

 3405, 3407. 3409. 34 IO > 34*5 and 3417). GSP BM 2543-4. 



