ILLUSTRATIONS IN THE TEXT. 



FIGS. PAGE 



26. — Problematic Nitella-like organism from the 



Silurian 73 



27. — Problematic organisms from the Devonian of 



North America ...... 74 



28. — Algites (Palseonitella) Crmiii, Kidst. & Lang. 76 



29.- — Palseochara acadica, Bell . ... 77 



30. — Kosmogyra swperba, Stache .... 82 



31. — Lagynophora, Stache ...... 83 



XI 



