PLATE LXXIV. 



Tig. 1. Development of a septum of Qoxiatitbs bicostatus, Hall. From the specimen fi^. 8 on plate 72. 

 Fij:. 2. Development of a septum of G. unianodlakis, Conrad. From the specimen fig. 14 on plate 71. 

 Fig^. 8. Development of a septum of G. discoidbds, Hall. From a young individual, represented on ^faUo 



71, fig. 4. 

 Fig. 4. Development of a septum of an adult specimen of G. discoidbds. Hall. Plata 71, fig. 13. 

 Fig. 6. Development of a septum of G. dnilobatds. Hall. Plate 71, fig. IB. 

 Fig. 6. Development of a septum of G. Chemdnqensis, Vanuxem. Plate 69, fig. 9. 

 Fig. 7. Development of a septum of G. Ltoni, Meek and Worthen. Plate 73, fig. 10. 

 Fig. 8. Development of a septum of G. simulator, Hall. Plate 69, fig. 1. 

 Fig. 9. Development of a septum of G. OwBHi, Hall. Plate 73, fig. 3. 

 Fig. 10. Development of a septum of G. OwH.vi, var. parallbla, Hall. Plate 73, fig. 1. 

 Fig. 11. Development of the left side of a septum of G. siNuosns, Hall. Plate 70, fig. 15. 

 Fig. 12. Development of the right side of a septum of G. Ixios, Hall. Plate 73, fig, 13. 

 Fig. 13. Development of a septum of G. pbracdtds. Hall. Plate 69, fig. 8. 

 Fig. 14. Development of a septum of G. Mithhax, Hall. Piute 69, fig. 7. 

 Fig. 15. Development of a septum of G. PAxaafiOKi, Hall. Plate 72, tig. 3. 



