180 FORAMINIFERA 



which may be divided into chamberlets in some species ; aperture 

 elongate, at the margin of the umbilical border of the chamber. 

 Carboniferous and Permian. 



Genus RUDITAXIS Schubert, 1920 

 Plate 53, figures 1, 2 



Genoholotype, ValvuUna 7-udis H. B. Brady 



Ruditaxis Schubert, Pal. Zeitschr., vol. 3, 1920, p. 180. 

 ValvuUna (part) H. B. Brady (not d'Orbigny), Pal. Soc. Mon. 30, 1876, 

 p. 90. 



Test in general structure like Tetrataxis but the chambers 

 labyrinthic; the wall more roughly and coarsely arenaceous. 

 Pennsylvanian and Permian. 



EXPLANATION OF PLATE 23 



Orbitolinidae 



Fig. 



1-4. Howchinia bradyana (Howchin). X 35. (After type figures). 

 Figs. 1, 3, Side views. Fig. 2, Vertical section. Fig. 4, Ventral 

 view. 

 5. Tetrataxis maxima Schellwien. X 15. (After type figure). 

 Partial section. 

 6, 7. Tetrataxis palaeotrochns Ehrenberg. X 30. (After H. B. Brady). 

 Fig. 6, a, dorsal view; h, ventral view; c, peripheral view. Fig. 

 7, Vertical section. 

 8-11. Valvnlinella ijonngi (H. B. Brady). X 30. (After type figures). 

 Fig. 8, Peripheral view. Fig. 9, Dorsal view. Fig. 10, Vertical 

 section. Fig. 11, Transverse section. 

 12, 13. Orbitolina concava, Parker and Jones. (After Egger). Fig. 12, 

 Vertical section. Fig. 13, Horizontal section. 



14. Dictyoconus puilboreauejisis Woodring. X 12. (After type figure). 



Vertical section. 



15. Chapmania gassinensis A. Silvestri. X 22. (After A. Silvestri). 



Vertical section. 



16. Cushmania americana (Cushman). X 22. (After type figure). 



Vertical section. 



17. Cyclolina cretacea d'Orbigny. X 4. (After type figure), a, dorsal 



view; b, peripheral view; c, same enlarged. 

 18-23. Dictyoconoides cooki (Cai-ter). Figs. 18-21, (After Carter). 

 Figs. 22, 23, (After Nuttall). Fig. 18, Exterior. Fig. 19, 

 Dorsal view. Fig. 20, Portion of base. Fig. 21, Portion of 

 vertical section. Fig. 22, Portion of surface layer. Fig. 23, 

 Vertical section. 



