60 EARLY TERTIARY OSTRACODA 



Holotype. Io. 4348, a female right valve (PI. 31, figs. 11). 



Paratypes. Io. 4297 + Io. 3099 + Io. 3141. 



Material. 14 specimens including the holotype from the Sor Range section from 

 one horizon (sample no. 460-i). GSP BM 2572-3. 



Type locality. Sor Range section. 



Type horizon. Upper Palaeocene, sample no. 460-i. 



Description. Sexual dimorphy rather strong ; the males are longer, less high and 

 less wide than the females. Carapace subrectangular to subquadrate in lateral view 

 with a slight taper towards the posterior. Dorsal margin slightly convex particularly 

 in the female, ventral margin almost straight, anterior broadly and evenly rounded, 

 posterodorsal slope very slightly concave, posteroventral margin rounded. Left 

 valve slightly over-reaches the right at the anterior margin. Subcentral-tubercle 

 distinct, eye-tubercle prominent, rounded and polished. Shell surface reticulate, the 

 reticulae are slightly papillose. The ventral ridge is present but not prominent, 

 sloping obliquely upward towards the posterior and culminating in the posterior 

 third. Marginal rim distinct. Anterior and posterior margins denticulate. Radial 

 pore canals simple, straight, slightly thicker on the proximal end, irregularly spaced, 

 about 30 anteriorly. Inner margin and line of concresence coincide. Dupiicature 

 fairly wide, 0-060 mm. anteroventrally. Selvage well-developed — submarginal in 

 left valve but almost in the middle in the right valve. There is a deep anterior and 

 ventral flange groove in the right valve. Hinge not clearly distinguished due to 

 mineralization but presumably holamphidont. 



Dimensions (mm). 



L 

 Io. 3099 Carapace male 0-65 



Io. 4297 Carapace female 0-47 



Io. 3141 Left valve female 0-46 



Io. 4348 Right valve female (holotype) 0-46 



Comparison. Phalcocythere retispinata sp. nov. is a closely related species but has 

 a reticulate and spinose surface, a more elevated ventral ridge and a well-developed 

 posterodorsal process. 



Phalcocythere retispinata sp. nov. 

 (Plate 31, figs. 13-17 ; Plate 32, figs. 1-3) 



Derivation of name. Latin rete, net + spinatus, spined ; with reference to the 

 surface ornamentation. 



Diagnosis. Phalcocythere with a prominent ventral ridge with alar expansion, 

 surface ornamentation a combination of reticulations and spines, subcentral-tubercle 

 present but not pronounced, eye-tubercle prominent, posterodorsal process well- 

 marked. 



Holotype. Io. 4345, a female carapace (PL 31, figs. 15, 16 ; PL 32, figs. 2, 3). 



Paratype. Io. 3165. 



H 



w 



o-35 



0-24 



o-35 



0-27 



o-35 



— 



o-35 



— 





