32 THE ENTOMOSTRACA OF 



Dorsal aspect elongate-subovate. 



This species closely resembles C. scabra, Minister, figured and described by Bosquet, 

 ' Descrip. Entom. Tert.,' p. 103, t. 5, fig. 7 ; but, instead of smooth tubercles, the latter 

 has ragged lamellar tubercles. Such exogenous growths as tubercles and spines are 

 subject to great variations of development, and must be used with caution for specific 

 characters ; still I prefer to regard the form under notice as distinct from C. scabra. 



Cythere scabropapulosa occurs at Bracklesham, and is rare. C. scabra, according to 

 Bosquet, belongs to the Subapennine deposits of the South of France, and the Miocene 

 beds of Dax ; Roemer derived it from the North-west of Germany (Osnabruck), and 

 from Bordeaux. 



No. 15. Cythere costellata, Roemer, sp. Plate V, fig. 11. 



Cytherina costellata, Roemer. Neues Jahrb. f. Min., &c, 1838, p. 517, t. 6, fig. 24. 

 Cythere costellata, Bosquet. Mem. Couron. Acad. Belg., xxiv, p. 58, t. 2, fig. 11. 



INCH. 



Length, -^ Middle Eocene : England and France. 



Carapace ovato-oblong ; rounded before, narrow behind ; dorsal border straight, 

 ventral slightly convex : valves most convex posterior to the centre, depressed ante- 

 riorly ; front and hind margins more or less denticulate ; surface covered by several 

 narrow, rounded, longitudinal, slightly sinuous ribs, placed side by side (10 or 1 1 in my 

 specimens, 7 or 8 in M. Bosquet's, and "about six" in M. Roemer's). 



Dorsal aspect elongate-acute- ovate; end-view ovate. 



A slight difference in the number of the superficial riblets exists amongst the 

 specimens figured and described, — as above noticed ; and there also appears to be a 

 somewhat greater convexity in Roemer's 6-ribbed form than in Bosquet's 7- or 8- 

 ribbed specimens, and in the latter than in my 10-ribbed specimens. 



Bosquet enumerates several localities for C. costellata in the " Sables moyens/' the 

 " Calcaire grossier," and in the " Sables inferieurs " of France. Roemer's specimens 

 also came from the Paris Tertiaries. In England I have only met with this species in 

 the sandy blue clay at Bracklesham, where a single specimen (perfect carapace) was 

 obtained. 



No. 10. Cythere plicata, Miinster. Plate IV, fig. 16 ; PI. V, figs. 8 a— 8 d; 



PI. V, fig. 17. 



