FROM WEST PAKISTAN 75 



height lies at the anterior cardinal angle, greatest length above the mid-point and 

 greatest width in the posterior third. Anterior and posterior cardinal angles pro- 

 jecting particularly in the left valve. Left valve slightly over-reaches the right valve 

 in the region of the anterodorsal corner and posterodorsal slope. Subcentral-tubercle 

 and eye-tubercle distinct. The most prominent part of the ornamentation is a large 

 slightly irregular hexagon formed of ridges just to the posterior of centre. Other 

 short ridges, mostly running outwards, join this hexagon at its corners. A sharply 

 curved ridge characteristic of the genus connects the eye-tubercle and the subcentral 

 tubercle. Dorsal ridge is broken in the middle and in the posterodorsal region it 

 extends vertically below to a point slightly above mid-line. The ventral ridge runs 

 at a slightly oblique angle towards the posterior end, its posterior portion forming the 

 ventral part of the hexagon. A high marginal rim runs on around the anterior margin 

 and continues along the ventral and posterior margins as a less high rim. Anterior 

 margin denticulate, postero ventral corner ornamented with a short spine. Dup- 

 licate e of moderate width with a strong selvage. Hinge holamphidont. 



Dimensions (mm). 



L H W 



Io. 4305 Carapace male o-6i 0-34 0-29 



Io. 4356 Carapace female (holotype) 0-56 0-34 0-29 



Comparison. It is easy to separate S. delineata from other described species of 

 the genus Stigmatocy there due to its characteristic surface ornamentation particularly 

 the large hexagon formed of ridges just to the posterior of centre. 



Stigmatocy there lumaria sp. nov. 

 (Plate 37, figs. 11 ; Plate 38, figs. 1-10 ; Plate 39, figs. 1-8, 11) 

 Derivation of name. Latin lumarius, thorny. 



Diagnosis. A species of Stigmatocythere with a prominent and bilobate subcentral- 

 tubercle. Surface tuberculate or combination of reticulations and tubercles. Three 

 large, projecting tubercles in the mid-dorsal region. 



Holotype. Io. 4354, a male carapace (PI. 38, figs. 1, 5, 8). 



Paratypes. Io. 4306-7 + Io. 3150-4. 



Material. Approximately 340 specimens from the Rakhi Nala section from 21 

 horizons (sample nos. 3621, 3624 to 3628, 3630, 3640 to 3642, 3645 to 3652, 3658, 

 3662 and 3663). 86 specimens from the Zao River section from 11 horizons (sample 

 nos. 24156, 24157, 24159, 24170, 24173 to 24176, 24180, 24187 and 24193). GSP BM 

 2592-94. 



Type locality. Rakhi Nala section. 



Type horizon. Upper Chocolate Clays, sample no. 3642. 



Description. Sexual dimorphism rather pronounced ; the females are shorter 

 and higher than the males. Carapace subrect angular in lateral view. Anterior 

 margin broadly rounded, posteroventral margin and posterior extremity more or 



