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PALAEOZOIC SYSTEM OF ROCKS. 



Palaeozoic times. 



Neozoic times. 



Quadripartita 



+ + Stemmed, or Crinoids. 

 + Armless, or simple arms. 



I 

 Radiata. 



Corals. 



| . . Sexpartita. 



Echinoderms. 



| . . Free, or Echinoids and Asteroids -f- + . 



Crinoids. 

 j . .Plumose arms. 



+ Brachiopods 



+ Square-shouldered . . . 



+ Unsiphonated 



Marine 



Unbeaked — Herbivorous. 

 Shelled, or Tetrabranchs. 



+ Straight 



Orthoceratites. 



N a u 



MOLLUSKS. 



Bivalves. 



| . . Lamellibranchs + + . 



Brachiopods. 



| . .Sloping-shouldered. 



Lamellibranchs. 



| . . Siphonated + . 



Gasteropods. 



| . . Land, fresh-water, and marine. 



Marine. 



| . . Beaked — Carnivorous + . 



Ccphalopods. 



| . . Naked, or Dibranchs + + . 



Shelled. 

 I ..Coiled. 



t i 1- 



Goniatites. 



Ceratites. 



Ammonites. 



Palaeocavida 



Articulata. 



I 

 Crustacea. 



.Neocarida +. 



Trilobites. 



Eurypterids. 



Limuloids. 



Macrourans. 



Brachyourans. 



I 

 Vertebkata. 



I 



Fishes. 



Heterocercals I . .Homocercals + . 



Ganoids and Placoids. ... | Tcleosts +. 



Placoids. 

 Cestracionts. 



Hybodonts 



Squalodonts. 

 Reptiles. 

 Amphibians j . . True Reptiles. 



early beaches he would have found cast up, in great numbers, the shells 

 of Brachiopods ; clinging to the rocks and hiding away among their 



