PLATE CLIX. 



FIGS. 



Oocardium stratum Nag. 1*, natural size ; 2-6 

 (after Senn) ; 2, vertical section through cal- 

 careous tubes, X 400 ; 3, tubes seen from above, 

 X 650 ; 4-6, X 1000 ; 7, newly-divided indi- 

 viduals, X 800 ; 8, stained to show pores, X 

 1200 (7 and 8 after Lutkemiiller) . . 204 



9-10. Sphcerozosma vertebratum (Breb.) Ralfs. 9, X 520 ; 



10, zygospores, X 400 (after Ralfs) . . 209 



II Sph. vertebratum var. latius W. & G. S. W. X 520 211 

 12. Sph. vertebratum forma minor West. X 400 . 210 

 13*. Sph. Aubertianum West. X 510 . 207 



Sph. Aubertianum var. Archeri (Gutw.) W. & G. S. 

 W. 14, x 520 ; 15, X ? (after Gutwinsld) ; 

 16*, X 510 ; 17, zygospores, X 520 . . 208 



