PLATE XJII. 



Figures magnified 500 diameters. 



I 'A ..I-:. 

 Fig. 1. DOCIDIOM VERTK'ILLATUM, . . . . .57 



" 2. DOCIDIUM COSTATUM, ...... 57 



" 3. DOCIDIUM GRACILE, large form ; whorls evidently composed of two 



rows of teeth, .... 58 



" 4. DOCIDIUM VEBRUCOSUM, vegetative state, . . . .56 



" 5. empty semi-cell, shows the arrangement 01 



the verrucae, . . . .56 



" 6. DOCIDIUM GRACILE, empty semi-cells, .... 58 

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



into parts, ..... 58 



" 8. " " small form, 58 



" 9. DOCIDIUM MINUTUM. Var. See Plate LXI, figs. 20-31. . 57 



" 10. DOCIDIUM TRIDENTULUM, . . . . . .57 



" 11. DOCIDIUM VERTICILLATUM, Var. turgidum, ... 57 



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



" 13. DOCIDIUM HIRSUTUM, ... 56 



