92 EARLY TERTIARY OSTRACODA 



(Bayliss, however, identified this as Nummulites crasseornata (Henrici) form B.) 

 This is in agreement with Eames, Bayliss and Latif . The ostracod faunal assemblages 

 below and above the irregularis Limestone are completely different and have no 

 species in common. These assemblages have been included in ostracod biostrati- 

 graphic Units II and III respectively. The Palaeocene and Lower Eocene boundary 

 in fact has been placed between these two biostratigraphic units. The ranges of 

 ostracod species found in the two biostratigraphic units are shown in Appendix 2. 



The Shales below the irregularis Limestone have a very rich assemblage of pelagic 

 Foraminifera and have been assigned to the Globrotalia rex Zone by Latif. Dr. 

 Banner, lately of the British Petroleum Co. Ltd., who very kindly examined these 

 samples, considers them to be of the high Globorotalia rex Zone with derived Lower/ 

 Middle Palaeocene pelagic Foraminifera. 



The Lower/Middle Eocene boundary in the Rakhi Nala, Zao River and Shpalai 

 Khwara sections has been placed at the base of the Platy Limestone. This is in 

 conformity with Eames, who examined the Rakhi Nala and Zinda Pir sections of the 

 Sulaiman Range. Bayliss and Latif, who worked on the Rakhi Nala section, how- 

 ever, have drawn the boundary in the uppermost part of the Lower Chocolate Clays 

 (i.e. below sample 3498). The Platy Limestone serves as an important horizon 

 marker in the region. The Lower/Middle Eocene boundary lies between ostracod 

 biostratigraphic Units IV and V, which have very different ostracod assemblages. 

 Except for Alocopocythere transcendens sp. nov., none of the Lower Eocene ostracod 

 species survive into the Middle Eocene. 



The Middle/Upper Eocene boundary in the Rakhi Nala and Zao River sections has 

 been placed between the lower and upper parts of the Upper Chocolate Clays. The 

 upper part of the Upper Chocolate Clays contains the genus Pellatispira, which is of 

 Upper Eocene age. In the Rakhi Nala section the boundary is taken arbitrarily 

 between samples 3627 and 3628. This is approximately the same level as drawn by 

 Eames (1952), who recorded the first appearance of Pellatispira just above this 

 horizon in the section. Bayliss, however, recorded Pellatispira only from one 

 horizon (sample 3657) in the Pellatispira Beds. Latif has placed the boundary in the 

 middle of his Chiloguembelina aff. martini Zone (i.e. above sample 3618). In the 

 Zao River section sample 24161 contains specimens of Pellatispira in abundance. 

 These have been assigned to Pellatispira orbitoidea (Povale) sensu Rao 1941 by Dr. 

 C. G. Adams of the British Museum (personal communication), who very kindly 

 examined these specimens. According to Dr. Adams these fall midway between 

 P. orbitoidea and P. madaraszi var. indica. The Middle/Upper Eocene boundary in 

 the Zao River section can, therefore, safely be placed below sample 24161. 



The Middle and Upper Eocene ostracod fauna of the Rakhi Nala and Zao River 

 sections is of changing suite and has been included in ostracod biostratigraphic 

 Unit V. It does not show any sharp break between the Middle and the Upper 

 Eocene. Some species are restricted to the Middle Eocene, but others range from 

 the Middle to the Upper Eocene. Some of the important species restricted to the 

 Middle Eocene are : Actinocythereis ? quasibathonica sp. nov., " Anommatocythere " 

 confirmata sp. nov., Echinocythereis (Scelidocythereis) rasilis sp. nov., Cytheropteron 

 sp.C, Gyrocythere exaggerata sp. nov., Trachyleberis (Trachyleberis) bimammillata 



