202 FORAMINIFERA 



KEY TO THE GENERA 



I. Adult test typically close coiled, planispiral, bilaterally symmetrical. 



A. Apertures at the base of the apertural face. 



1. Single, sutures simple N onion. 



2. Usually several, sutures with bridges Elphidium. 



B. ■ Apertures partly in the apertural face. 



1. Aperture, a single rounded opening in the middle of the face. 



Orbignyna. 



2. Aperture consisting of numerous rounded ^loves.. .Cribrospira. 



3. Aperture with concentric rows of elongate pits Bradyina. 



II. Adult test somewhat trochoid. 



A. Last-formed chambers extending toward and often covering the 



umbilicus at one side Nonionella. 



B. Test in the adult typically trochoid, planoconvex. 



1. Dorsally convex, ventrally flattened Polystoinellina. 



2. Dorsally flattened, ventrally convex Faujashm. 



EXPLANATION OF PLATE 27 



nonionidae 



Fig. 



1. Nonion incrassatus (Fichtel and Moll). (After type figure), a, 



side view; b, peripheral view. 



2. Nonion turyid^is (Williamson). X 50. (After H. B. Brady), a, 



side view; b, apertural view. 



3. Nonion umbilicatulus (Montagu), x 50. (After H. B. Brady). 



a, side view; b, apertural view. 



4. Crihrospira panderi Moller. X 20. (After type figure), a, 



apertural view; b, from opposite periphery; c, side view. 



5. Bradyina rotula (Eichwald). X 20. (After Moller). a, aper- 



tural view; b, side view. 

 G, 7. Bradyiyia nautiliforrnis Moller. (After type figures). Fig. 6, X 

 12. Fig. 7, Section. X 20. 



8. Nonionella miocenica Cushman. X 50. (After type figure), a, 



dorsal view; b, ventral view; c, apertural view. 



9. Elphidium macellus (Fichtel and Moll). (After type figure), a, 



side view; b, apertural view. 



10. Elphidium craticulatus (Fichtel and Moll). (After H. B. Brady). 



a, side view; b, apertural view. '' 



11. Polystomellina discorbinoides Yabe and Hanzawa. X 40. (After 



type figure), a, dorsal view; b, ventral view; c, peripheral view. 



12. Faujasina carinata d'Orbigny. (After type figure), a, ventral 



view; 6, dorsal view; c, peripheral view. 



