L 



H 



W 



o-57 



0-32 



0-24 



o-57 



o-34 



0-29 



66 EARLY TERTIARY OSTRACODA 



Type locality. Sor Range section. 



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



Description. Carapace subrectangular in the male dimorph and subquadrate in 

 the female. Sexual dimorphism rather apparent ; the females are higher and wider 

 than the males. Carapace compressed in the posterior region. Anterior margin 

 broadly rounded, posterodorsal slope very slightly curved, posterior almost rounded, 

 post ero ventral margin slightly curved. The ornamentation over-reaches the dorsal 

 margin giving a jagged appearance, ventral margin almost straight in the male but 

 slightly curved in the female. Left valve very slightly over-reaches the right at the 

 posterodorsal slope and at the anterior cardinal angle. In dorsal view the greatest 

 width is situated anterior to the middle. Subcentral-tubercle prominent, eye-tubercle 

 distinct. A marginal rim runs around the anterior, ventral and posterior margins. 

 It is upraised around the anterior but less elevated along the venter and around the 

 posterior end. Surface reticulate with a well-marked ventral ridge giving rise to an 

 expanded venter. At the posterodorsal corner a small horn-like projecting ridge is 

 present. Anterior margin ornamented by small, numerous denticles (20-25 in 

 number) but the posterior has only a few denticles. 



Dimensions (mm). 



Io. 4351 Carapace male (holotype) 

 Io. 4300 Carapace female 



Comparison. Quadracythere {Hornibrookella) directa sp. nov. is larger, has a less 

 well-developed subcentral-tubercle and lacks an expanded venter. 



Remarks. The preservation of the material prevents a description of the internal 

 characters. So far this species is only known from the Upper Palaeocene of the Sor 

 Range section. 



Quadracythere (Hornibrookella) directa sp. nov. 

 (Plate 33, figs. 16, 17 ; Plate 34, figs. I, 2) 



Derivation of name. Latin directus, rectangular ; with reference to the outline 

 in lateral view. 



Diagnosis. In lateral view carapace subrectangular with protruding anterior and 

 posterior cardinal angles. Surface ornamentation consists of reticulation with an 

 oblique ventral ridge sloping upward towards posterior and a short horn-like ridge at 

 posterodorsal corner. Sexual dimorphism pronounced. 



Holotype. Io. 4350, a female carapace (PL 33, figs. 17 ; PI. 34, fig.2). 



Paratype. Io. 4301. 



Material. 96 specimens from the type locality from four horizons (sample 

 nos. 3184, 3192, 3402 and 3403) . GSP BM 2583-4. 



Type locality. Rakhi Nala section. 



Type horizon. Green and Nodular Shales, sample no. 3403. 



