112 



POST-TERTIARY ENTOMOSTRACA. 





SHAPE AS SEEN LATERALLY. 



TEXTURE AND MARKINGS OP 

 SHELL. 



HINGEMENT. 



Cypkid^ — 









Macrocypris ... 



Elongated, attenuated bebind, 



Robust, perfectly smooth 



Flexuous, formed by the overlapping 





subtriangular, rigbt valve larger 





right valve. 





than left, and overlapping 







Goniocypris ... 



Triangular, heigbt and lengtb 



Very thin and fragile, almost 



Simple. 





about equal, minute 



structureless 





Darwinellada: — 









Darwinella 



Compressed, oblongo-ovate or 

 subcuneate, valves unequal, 

 rigbt mucb larger tban left 



Thin, quite smooth, pellucid 



Simple. 



Cytherid^e — 









Metacypris 



Subrbomboidal, supero-posterior 



Moderately robust, closely punc- 



On right valve, by a laminated angular 





angle produced 



tate 



process in front, behind by a strong 

 flange with a single tooth, the flange 

 continued round posterior margin, 

 on left valve by a deep sulcus behind 

 and a shallow one in front. 



Limnicytbere ... 



Reniform or subreniform 



Moderately robust, angularly 



Simple, or with a very feebly marked 







pitted, prominently tubercu- 



arrangement, as in the next genus. 







lated or spinous 





Cytbere 



Subreniform or subquadrate, 

 mostly highest in front 



Robust, often excessively thick 

 and calcareous, smooth or 



Two strong teeth on the right, with 

 corresponding depressions on the left 









variously sculptured vrith fine 



valve, between the teeth often a 







punctations or large and deep 



strong longitudinal bar and between 







fossae, tubercles, spines, ele- 



1 



the fossae a furrow, left valve some- 







vated ridges, &c. 



times with a small tooth behind each 

 fossa. 



Cytberidea 



Subtriangular or triangularly 



Usually thick and strong, smooth. 



Two series of terminal crenulated tu- 





ovate, highest in front of the 



or more commonly foveolate; 



bercles on right, with corresponding 





middle 



sometimes concentrically ru- 



depressions of left valve ; interme- 







gose, with dentate margins 



diate portions either plain or tuber- 

 culated on left and indented on right 

 valve. 



Eucy there 



Subtriangular, high and rounded 



Thin and pellucid, bearing con- 



Formed on right valve by a projecting 





in front, depressed behind 



spicuous rounded papillae 



crest, on left by a corresponding 

 depression. 



Krithe 



Subovate, oblong, truncate be- 



Smooth, with small distant 



Like Eucy there, but feebly developed. 







hind 



papillae 





