112 POST-TERTIARY ENTOMOSTRACA. 





SHAPE AS SEEN LATERALLY. 



TEXTURE AND MARKINGS OF 

 SHELL. 



HINGEMENT. 











Macrocypris ... 



Elongated, attenuated behind, 

 subtriangular, right valve larger 

 than left, and overlapping 



Robust, perfectly smooth 



Plexuous, formed by the overlapping 

 right valve. 



Goniocypris ... 



Triangular, height and length 

 about equal, minute 



Very thin and fragile, almost 

 structureless 



Simple. 



T) A 1? WTNF.T.T, AT) 









Darwinella , , 



Compressed, oblongo-ovate or 

 subcuneate, valves unequal, 

 right much larger than left 



Thin, quite smooth, pellucid 



Simple. 



Cytherid^; — 









Metacypris 



Subrhomboidal, 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. 



Limnicythere ... 



Reniform or subreniform 



Moderately robust, angularly 

 pitted, prominently tubercu- 

 lated or spinous 



Simple, or with a very feebly marked 

 arrangement, as in the next genus. 



Cythere 



Subreniform or subquadrate, 



Robust, often excessively thick 



Two strong teeth on the right, with 







mostly highest in front 



and calcareous, smooth or 

 variously sculptured with fine 

 uuiiLiaiioiis or large aiiu ueep 

 fossae, tubercles, spines, ele-| 

 vated ridges, &c. 



corresponding depressions on the left 

 valve, between the teeth often a 

 strong longitudinal bar and between 

 the fossae a furrow, left valve some- 

 times with a small tooth behind each 

 fossa. 



Cytheridea 



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- 

 gose, with dentate margins 



depressions of left valve ; interme- 

 diate portions either plain or tuber- 

 culated on left and indented on right 

 valve. 



Eucythere 



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 Eucythere, but feebly developed. 







hind 



papillae 





