18 EARLY TERTIARY OSTRACODA 



Alocopocythere coarctata sp. nov. 



(Plate 4, figs. 2-9) 



Derivation of name. Latin coarctatus, " pressed together " ; with reference to 

 the carapace. 



Diagnosis. Alocopocythere in which carapace in lateral outline appears to be 

 compressed ; dorsal and ventral margins tapering towards the posterior end, sub- 

 central-tubercle distinct, anterior marginal rim high, surface finely reticulate (with 

 superimposed weak longitudinal ridges) . 



Holotype. Io. 4313, a female carapace (PI. 4, figs. 6-9). 



Paratype. Io. 4264. 



Material. 49 specimens from the below locality from five horizons (sample 

 nos. 3432, 3434, 3435, 3458 and 3459) . GSP BM 2513-4. 



Type locality. Rakhi Nala section. 



Type horizon. Shales with Alabaster, sample no. 3458. 



Description. Carapace subrectangular to subquadrate in lateral view. Sexual 

 dimorphism strong ; the females are shorter than the males. Anterior margin 

 broadly and evenly rounded, posterodorsal margin straight, particularly in the left 

 valve, posterior extremity rounded, posteroventral margin rounded. Dorsal margin 

 sinuous with a hump between the protruding anterior and posterior cardinal angles, 

 ventral margin slightly concave in the middle. Both dorsal and ventral margins 

 taper towards the posterior. Valves almost equal. Surface finely reticulate with 

 superimposed weak longitudinal ridges. Subcentral-tubercle distinct, eye-tubercle 

 more or less distinct. Marginal rim present, elevated in the anterior, less elevated 

 round the venter and posterior. Anterodorsal furrow fairly distinct and is bounded 

 anteriorly by a short almost vertical ridge. Anterior and posterior margins denticu- 

 late. Internal characters not known. 



Dimensions (mm). 



L 



Io. 4264 Carapace male 0-51 



Io. 4313 Carapace female (holotype) 0-50 



Comparison. Unlike A. coarctata, Alocopocythere rupina sp. nov. has better 



developed longitudinal ridges and coarser reticulation. In addition, these two 



species differ in lateral outline, particularly the male dimorphs. Alocopocythere 



transcendens , sp. nov. is larger, has a less well-developed hump between the protruding 



anterior and posterior cardinal angles and lacks longitudinal ridges. 



Alocopocythere longilinea sp. nov. 



(Plate 4, figs. 10-13 ; Plate 5, figs. 1-3, 6) 



Derivation of name. Latin longi, longitudinal + linea, line. 



Diagnosis. A small Alocopocythere in which surface ornamentation is reticulate, 



H 



W 



0-27 



0-27 



0-32 



0-29 



