LIST OF ILLUSTBATIONS. 



Frontispiece. Encrinite. Apiocrinus rotundus. 

 1. Seaweed. Fucus canaliculatus . . . 



Fucus vesiculosus ...... 21 



Fucus serratus ...... 22 



Fucus nodosus ...... 24 



Halidrys siliquosa ...... 25 



Plocamium coccineum ..... 27 



7. Diatom. Navicula didyma ...... 30 



8. Pleurosigma formosum ..... 33 



9. Graptolite. Didymograptus Murchisoni ... 52 



10. Sea Fir. Sertularia fusca, with calycles ... 53 



11. Sertularia abietina, calycles and capsule . 55 



12. Magnified Calycles of Graptolite ..... 55 



13. Double Graptolite. Diplograptus pristis ... 56 



14. Silurian Encrinites. Marsupiocrinus ccelatus. Arms 



and proboscis of ditto. Crotalocrinus rugosus. 



Pelvis, stomach, and arms of ditto .... 75 



15. Head of Encrinite. Poteriocrinus .... 76 



16. Trilobite. Phacops caudatus ..... 94 



