114 



POST-TERTIARY ENTOMOSTRACA. 





SHAPE AS SEEN LATERALLY. 



TEXTURE AND MARKINGS OF 

 SHELL. 



HINGEMENT. 



CYTHERIDiE — 









Paradoxostoma 



Elongated, compressed, usually 



Thin, fragile, polished, and de- 



Simple. 





mgher behind than in front ; 



void of sculpture, but often 







usually subovate, subtriangular, 



marked with arborescent co- 







or flexuous 



I 1 j1 Pill 1' 



loured patches or black, olive, 









or violet hue 





Cypridinad^ — 









Cypridina 



Subcircular or very broad oval, 



Smooth, thin, and flexible 



Nearly simple. 





with a distinct beak and notch 









in front and a slight projection 









behind 







Brady cinetus ... 



Similar to the foregoing, beak and 



Dense, punctate 



Nearly simple. 





notch well developed 







rnilomedes 



Similar to the above, posterior 



Moderately strong, punctate, or 



Nearly simple. 





extremity usually with one or 



foveate and ribbed 







two spines 







Asterope 



Elongated, beak not at all pro- 



Moderately strong, smooth 



Nearly simple. 





duced, posterior extremity 









evenly rounded 







Eurypylus 



Beak obsolete, no distinct notch ; 



Robust, more or less pitted 







seen from above widest in 









front 







POLYCOPID^ — 











Circular or nearly so, no notch or 



Thin, calcareous, smooth, punc- 



11 1*1a 1 • AJi 



formed by a slight overlapping of the 





beak 



tate, or reticulate 



valves. 



Cytheeellid^— 









Cytherella 



Usually elliptical, compressed. 



Thick and dense, smooth or 



A groove on the right valve into which 





valves very unequal, the right 



variously sculptured 



the edge of the left is received. 





much the larger 







Bosquetia 



Obliquely and broadly ovate, right 



Very thick and hard, smooth 



Formed by an overlapping (?) of the 





valve much larger than left, and 





right valve at each extremity. 





overlapping both above and 









below 







