PLATE XIV 



Orbiculina. 



Diam. Page 



Figures 1-13. — Orbiculina adunca, Fichtel and Moll, sp., . . 209 



Figs. 1, 2. Very young or nautiloid condition ; — 



Nautilus angulatus, Fichtel and Moll, . x 30 



Figs. 3, 4. Varieties analogous to the " Spiroline " 



modifications of Peneroplis, . x 30 



Figs. 5, 6. Specimens in the young or intermediate 



stage ; — Nautilus orbiculus, Fichtel and Moll, . x 30 



Figs. 7, 8. Flabelliform adult shells ; — Nautilus 



aduncus, Fichtel and Moll, . x 20 



Fig. 9. Adult specimens, discoidal form ; — Orbiculina 



compressa, d'Orbigny, . . x 20 



(b, b, b, peripheral aspect of the various forms.) 



Figs. 10, 11, 12. Transverse sections of shells in 

 different stages of growth, showing the embrac- 

 ing character of the earlier chambers, . . x 20-30 



Fig. 13. Section of the shell more highly magnified, 



showing the superficial pnnctation, . . x 100 



