267 



42. CYTHERIDEA DOLABRA,* Sp. 11. 



PI. iii., figs. 3 a, h, c. 



Dorsal margin straight in the middle, strongly sloping towards 

 each end from the hinge-angles ; the posterior slope incurved 

 like that of a Bairdia. Ventral margin rounded before and 

 behind, and incurved in the middle. Surface smooth, but marked 

 with scattered pits, as in the two foregoing species. Edge view, long 

 acute-ovate ; end view, acute-ovate. Hingement, as in pi. i., fig. 2. 



Eeuss' G. notaia (Haidinger's Nat. Abth., vol. iii., 1850, pi. ix., 

 fig. 16), approaches this fc«-m ; but Eeuss' species has a strong 

 antero-ventral notch, and a curved transverse mid-dorsal ridge, 

 dying out towards the antero-ventral region. 



Four examples ; Blue Fullers-earth Clay, Midford. 



43. CYTHERIDEA TRANSVERSIPLICATA, Sp. 71. 



PI. iii., figs. 4 a, b, c. 



Broadly curved anteriorly, angulate behind. Dorsal margin 

 almost straight, but slightly projecting at the anterior hinge. 

 Ventral margin sinuous, being incurved in the middle. The valve 

 has somewhat the outline of the sole of a human foot. Surface 

 smooth, but with numerous small transverse undulations (well 

 seen in the edge view), and marked all over with large, irregular, 

 shallow pits. Edge view, bluntly lanceolate, with wrinkled 

 outline ; end view, oval. Hingement, the same as pi. i., fig. 2. 



One specimen ; Blue Fullers-earth Clay, Midford. 



44. CYTHERIDEA EGREGIA, sp. n. 



PI. iii., figs. 5 a, b, c. 



Nearly allied to the last, but broader, more oblique anteriorly, 

 and rather less angular behind. Surface beariag faint cross 



* An axe. 



