PLATE XIII. 



Figures magnifled 500 diameters. 



Page. 

 Fig. 1. DoCIDinM VERTICrLLATUM, . . .57 



" 2. DOCIDIUM COSTATUM, . . . . 57 



" 3. DociDlUM 6EACILE, large form ; whorls evidently composed of two 



rows of teeth, ... 58 



" 4. DociDiDM VERRUCOsnM, Vegetative state, . . 56 



" 0. " " empty semi-cell, shows the arrangement oi 



the verrucae, ... 56. 



" 6. DociDiUM GRACILB, empty semi-cells, ... 58 

 " 7. " " empty semi-cell, older condition before breaking 



into parts, . ... 58 



" 8. " " small form, ... .58 



" 9. DoclDiDM MINDTUM, Var. See Plate LXI, figs. 29-31. . . 57 



" 10. DoCIDIDM TRIDENTULDM, . . .57 



" 11. DociDiTjM VEETiciLiiATDM, Var. turgidum, ... 5? 



" 12. DOCIDIUM SPINOSUM, . . . . . 56 



" 13. DoCIDITJM HIESUTDM, ... .56 



