4 
Pakmster'.Tceniaster, Pleurocystis (EcnmoiDs); Graptolithus ; Favosites, 
llalysites, Ghcetetes, Golumnaria, Tetradium (Zoan. tab.) ; Petriia, Stro- flG 
matocerium (Zoan. rugosa) ; Eospongia, Astylospongia, Astrmspongia , 
(Sponges) Arthroclema (Fucoid). 
Upper Silurian ( Murchisonien ). 
8. Niagara Period ; 9, Salina (Onondaga Salt); 10, Lower Hel- 
DERBERG. 
First appearance of Homalonotus, Phacops (Tril.) ; Spirifera, 
Atrypa, Merista, Ghonetes, Grania * (Brach.) Actinocrinus. 
Disappearance of Graptolites ; Galymene, I Harms, Acidaspis ; 
Ilalysites. Decline of Orthoceras; Cystideans. • 
Rign of Tetrabranchs with simple septa; Brachiopods; Cri- 
noids ; Coral animals. 
Period of Galymene, Lidias, Acidaspis, Illcenus, Dalmania (Tril.) ; 
Eurypterus (Entomostracan] ; Lituites, Cyrtoceras, Gomphoceras, Or¬ 
thoceras, Gonularia; Platyceras, Platyostoma, Subtdites, Eolopea 
(Gaster.) ; Gonocardium, Pterinea, Modiolopsis, (Lamell.) ; Rhynchon- 
ella, Pentamerus, Sperifera, Atrypa Merista, Meristella (Brach.) ; 
Fenestella, Ptilodictya, Phcenopora, Ilelopora, etc., (Bryozoans) ; Garry- 
ocrinus, Ichthyocrinus, Stephanocrinus, Actinocrinus, Rhodocrinus, 
Eucalyptocrinus, Tentaculites (Crinoids) ; Fawsites, Holy sites, Helio- 
lites, Gladopora, Stromatopora (Corals) ; Ischadites, Receptaculiles 
(Foraminifera). 
In the uppermost beds of the Silurian are found, in Great Britain, 
the small icthyolites called Plectrodus mirdbilis and Onchus Murchisonii; 
and on the island of (Esel in the Baltic, Thyestes verrucosus and Gephal- 
aspis SchrenMi. No Silurian Fish-remains are known in America. 
IV. BEVOWIAN AGE ["Old Red Sandstone ; Devonien .] 
Frst appearance of Fishes (in America) and Decapod (10- 
footed) Crustaceans (in Europe). Culmination of Cyathophyl- 
loids. 
Reign of Fishes and Coral-animals. 
LowerDevonian. 11$ Oriskany Period; 12, Corniferous. 
First appearance of Fishes [in Corniferous] ; ,Productus; broad¬ 
winged Spirifers. 
Disappearance of Cystids [in Oriskany] ; Favistella, Ileliolites. De¬ 
cline of Trilobites and Orthoceratites. 
Reign of Fishes ; Coral-reef Polyps ; Atrypa reticularis. 
Period of the Cup-corals Gyathophyllum , Zaphrentis, Glisiophyllum, 
Blothrophyllum, Amplexus, Ghonophyllum [Zoan, rugosa] ; and the 
other corals, Favosites, Michelinia, Syringopora, Aulopora, Ileliolites, 
PLaimeophyllum, Eridophyllum ; Nucleocrinus; Atrypa, Spirifer, Stro- 
phomena, Ghonetes, Productus, Pentamerus, Leptoccelia, Gentronella, 
Gharionella [Brack.] ; Gonocardium trigonale, Lucina * proavia ; Gyr- 
toceras, Gomphoceras ; Dalmania, Proetus [Tril.] ; Macropetalichthys, 
Machceracanthus, Onychodus, Psammodus, Oracanthus, Palceoniscus 
[American Fishes]. 
The Devonian Fishes are Cestraciont Sharks * [with bony pave¬ 
ment teeth], and Ganoids of the groups Placoganoids * (Sturgeon¬ 
like), Rhombifers * [like the Garpike], Imbricates * (like Amia — 
the fresh-water Dog-fish). All have veftebrated tails ; and the Gan¬ 
oids possess reptilian conformations. 
Upper Devonian. 13, Hamilton Period— represented by Marcel- 
lus Shale, Hamilton proper and Genesee Shale [Black “ Slate” of the 
West]; 14, Chemung Period [Huron Group of Mich.]—represented 
