34 EARLY TERTIARY OSTRACODA 



Type species. Echinocythereis (Scelidocythereis) multibullata. sp. nov. 



Echinocythereis (Scelidocythereis) multibullata sp. nov. 

 (Plate 16, figs. 3-9 ; Plate 17, figs. 1, 2, 7) 



Derivation of name. Latin multus, much + bullatus, knobbed ; with reference 

 to the ornamentation. 



Diagnosis. A species of the subgenus Scelidocythereis with a prominent sub- 

 central-tubercle consisting of 4-5 small nodes. Surface nodose or tuberculate. 

 Right valve over-reaches left valve anteriorly but is over-reached by the latter at 

 anterior and posterior cardinal angles. 



Holotype. Io. 4328, a male carapace (PI. 16, figs. 3, 5, 6 ; PI. 17, fig. 7). 



Paratypes. GSP BM 2558-I0. 3133-4 + Io. 4277. 



Material. 76 specimens from the Zao River section from five horizons (sample 

 nos. 24154, 24156, 24159, 21461 and 24183). 28 specimens from the Rakhi Nala 

 section from three horizons (sample nos. 3621, 2624 and 2625). GSP BM 2535-6. 



Type locality. Zao River section. 



Type horizon. Upper Chocolate Clays, sample no. 24161. 



Description. Sexual dimorphism rather marked ; presumed females shorter, 

 higher and wider than presumed males. Carapace subrectangular in lateral view. 

 Anterior margin broadly and evenly rounded in both valves. In the right valve the 

 posterodorsal corner is very slightly concave, whilst the posterior extremity and the 

 posteroventral margins are rounded ; in the left valve the posterior end is truncated. 

 Dorsal margin intricate in lateral view because of ornamentation ; ventral margin 

 slightly incurved anterior to the middle in the right valve but curved convexly down- 

 ward in the left valve. Greatest length passes through the middle, greatest height 

 at the anterior cardinal angle and greatest width in front of the middle (i.e. at the 

 subcentral-tubercle). Anterior cardinal angle protruding. Right valve over- 

 reaches the left at the anterior margin and posteroventral margin ; but left valve 

 over-reaches the right in the region of the anterior and posterior cardinal angle. 

 Subcentral-tubercle prominent and is composed of 4-5 small nodes. Eye-tubercle 

 rounded and distinct. Surface ornamented with nodes, or tubercles, those nearest 

 the ventral margin being the larger. There are three small ventral ridges, the two 

 near the ventral margin are smaller and almost confined to the anteroventral and 

 mid-ventral regions. Anterior and posterior margins are denticulate. Viewed 

 internally the valves are deep. Duplicature fairly wide, o-n mm. at the posterior 

 extremity (PI. 16, fig. 9). Selvage well-developed, subperipheral in the left valve but 

 almost at the outer third in the right valve. A deep flange groove, better developed 

 at the venter, lies between the selvage and flange in the right valve. Radial pore 

 canals fairly numerous, simple, almost straight, few occurring in groups of two or 

 three. Inner margin and line of concrescence coincide. Muscle scars (best seen in 

 weathered specimens from the outside) are in an almost vertical column of four 

 adductors and two more or less rounded frontal scars. Hinge holamphidont : 



