L 



H 



W 



o-47 



0-24 



— 



o-43 



0-22 



0-13 



o-43 



0-24 



o-i6 



54 EARLY TERTIARY OSTRACODA 



median part of the carapace (halfway between the dorsal and ventral ridges) in a few 

 specimens. A high marginal rim runs round the anterior extending along the venter 

 and posterior as a less high rim. Anterior and posterior margins ornamented with 

 short spines. Duplicative wide in anterior and posteroventral regions. Selvage 

 distinct and lies at some distance from the outer margin. Radial pore-canals and 

 muscle scars not determinable. Hinge as for the genus. 



Comparison. Occultocythereis mutabilis abducta Triebel (1961) is very similar, but is 

 larger, has a different posterior end, less well-developed subcentral-swelling and 

 posterodorsal tubercle. Occultocythereis mutabilis mutabilis Tiebel (1961) has a 

 vertical posteroventral ridge in the right valve of the male and in both valves of the 

 females. 



Dimensions (mm). 



Io. 4294 Right valve male 



I°- 3 X 35 Carapace male 



Io. 4340 Carapace female (holotype) 



Remarks. 0. indistincta has so far been found in the Lower and Upper Chocolate 

 Clays of the Rakhi Nala section. 



Genus PAT AGON ACY THERE Hartmann 1962 



Type species. Patagonacy there tricostata Hartmann 1962. 



Remarks. The species here assigned with query to Patagonacy there differs in 

 details of muscle scar pattern both from the type species described by Hartmann and 

 from the two species described by Benson (1964) from the Antarctic. In common 

 with the described species it shows the three longitudinal ridges in which a characteris- 

 tic posterodorsal loop joins the upper two. 



Patagonacy there ? nidulus sp. nov. 

 (Plate 28, figs. 5-12 ; Plate 29, figs. 1-4) 



Derivation of name. Latin nidulus, small bird's nest ; with reference to the 

 reticulate complex of the subcentral node. 



Diagnosis. Carapace highly reticulate in which ventral ridge culminates ab- 

 ruptly in posterior third, subcentral-tubercle prominent. 



Holotype. Io. 4349, a female carapace (PI. 28, figs. 9-12). 



Paratypes. Io. 4295 + Io. 3096-8. 



Material. Over 400 specimens from the Zao River section from 16 horizons 

 (sample nos. 24155 to 24157, 24159, 24166, 24170, 24173, 24175 to 24178, 24180, 

 24183, 24185, 24187 and 24193). Approximately 60 specimens from the Rakhi 

 Nala section from 13 horizons (sample nos. 3624, 3625, 3628, 3631, 3634, 3640 to 3642, 

 3645, 3646, 3649, 3658 and 3662). GSP BM 2568-9. 



