Geol.Mag,1885. 



Decade III. Vol.11. PI. IX. 



E.CWooiweuriKtk. 



West.NewmanStCo iTn.p. 



Fi g s . 1 — 6 . Aptychi , D evonian , Bicken. ,Nas s aca . 

 Figs.7— 11 .Silurian Chitons. Fig. 12 ."Recent Chiton. 



