16 EXPLANATION OF THE FIGURES. 



FlO. 



150. Cornatula, a "West India species, in its early stage, with, its stem 



151. The same detached, and swimming free. 



152. Longitudinal section of the sturgeon, to show its cartilaginous ver 



tebral column. 



153. Amphioxus, natural size, showing its imperfect organization. 



154. Section of the earth's crust, to show the relative positions of the 



rocks composing it ; E, plutonic or massive rocks ; M, metamor- 

 phic rocks ; T, trap rocks ; L, lava. 1. Lower Silurian forma- 

 tion ; 2. Upper Silurian ; 3. Devonian ; 4. Carboniferous ; 5. 

 Trias, or Saliferous ; 6. Oolitic ; 7. Cretaceous ; 8. Lower Terti- 

 ary or Eocene ; 9. Upper Tertiary, or Miocene, and Pleiocene ; 

 10. Drift. 



155. Fossils of the Palaeozoic age ; a, Lingula prima ; b, Leptsena alter- 



nata ; c, Euomphalus hemisphericus ; d, Trocholites ammonius ; 

 e, Avicula decussata ; f t Bucania expansa ; g, Orthoceras fusi 

 forme ; i, Cyathocrinus ornatissimus, Hall ; j, Cariocrinus orna- 

 tus, Say ; k, Melocrinus amphora, Goldf. ; I, Columnaria alveo , 

 lata ; m, Cyathophyllum quadrigeminum, Goldf. ; n, o, Caninia 

 flexuosa ; p, Chaetetes lycoperdon. 



156. Articulata of the Pakeozoic age ; a, Harpes ; b, Arges ; c, Brontes , 



d t Platynotus ; e, Euryptei;us remipes. 



157. Fishes of tbe Palaeozoic age ; a, Pterichthys ; b, Coccosteus ; c t 



Dipterus ; d, palatal bone of a shark ; e t spine of a shark. 



158. Representations of the tracks of supposed birds and reptiles in the 



sandstone rocks. 



159. Supposed outlines of Ichthyosaurus, (a,) and Plesiosaurus, (b.) 



160. Supposed outline of Pterodactyle. 



161. Shells of the Secondary age; a, Terebratula; b, Goniomya; c, 



Trigonia ; d, Ammonite. 



162. Supposed outline of the cuttle-fish, (a,) furnishing the Belemnite. 



163. Radiata from the Secondary age ; a, Lobophyllia flabellum ; b, Litho- 



dendron pseudostylina ; c, Pentacrinus briareus ; d, Pterocoma 

 pinnata ; e, Cidaris ; f t Dysaster ; g, Nucleolites. 



164. Shells of the Cretaceous formation ; a, Ammonites ; b, Criocerns j 



c, Scaphites ; d, Ancyloceras ; e, Karaites ; /, Baculites ; g, 

 Turrilites. 



165. Shells of the Cretaceous formation ; a, Magas ; 5, Inoceramus ; >, 



Hippurites ; d, Spondylus ; e, Pleurotomaria. 



166. Radiata from the Cretaceous formation ; a, Diploctenium cordatura 



6, Marsupites ; d, Galerites ; c, Salenia ; e Micraster con 



anguinum. 

 167 Nummulite. 

 168. Supposed outline of Paleotherium. 



169 Supposed outline of Anoplotherium. 



170 Skeleton of the Mastodon, in the cabinet of Dr. J. C. Warren. 



