APPENDIX. 759 



—103, 104 Tilted or dislocated strata; folds or flexures.— 105. Outcrop; dip; 

 strike; anticlinal; synclinal. — 106. Clinometer. — Faults. — Results of denuda- 

 tion in obscuring the order of stratification. — 110. Calculating thickness of 

 strata. — 111. Unconformable strata. — 112, 113. Difficulties in the way of de- 

 termining the order of arrangement of strata. — 113-115. Three means of deter- 

 mination. — 115. Principles on which the value of fossils depends. — 116. Ages in 

 Geology. — 117-119. Unstratified rocks : examples. — 119. General nature of 

 Veins. — 122. Dikes. — 123. Simple and banded veins. 



V. Historical Geology. — Azoic Time. — Pages 125, 126. Three principles 

 characterizing subdivisions in all history, whether the limits of an Age are 

 marked or not in the rocks. — 127. Fourth principle. — Fifth principle. — 128. Sixth 

 principle; use of the word equivalent. — 128. True basis of the subdivision into 

 Geological Ages. — 130. The Ages. — The five higher divisions of Time, and their 

 signification. — Basis of the subdivisions into Periods and Epochs. — 134. Cha- 

 racteristic and reality of the Azoic Age. — 136. Distribution in North America. 

 — 138. Kinds of rocks. 140. Prevalence of iron-ore. — 140-142. Arrangement 

 of the rocks. — 143. Their original condition. — Disturbances and foldings. — 144. 

 Proof that there were long ages of quiet in the course of Azoic Time. — 145. 

 Alterations or metamorphism of the rocks ; examples. — The existence or not of 

 life in the Azoic Age. — 147. First expression of the idea of life. — Relations of 

 the North American Azoic to the present continent. 



VI. Animal Kingdom. — Page 147. Names of the four Sub-kingdoms of ani- 

 mals. — Characteristics of Radiates, and examples. — 148. Id. of Mollusks. — 149. 

 Id. of Articulates. — 151. Id. of Vertebrates. — Recapitulation. — 152. Protozoans. 

 — Names of Classes of Vertebrates. — Characteristics of Mammals, and examples. 

 — Id. of Birds. — Id. of Reptiles. — Id. of Fishes. — Names of Classes of Articu- 

 lates. — Characteristics of Insects, and examples. — Id. of Spiders. — Id. of Myria- 

 pods. — 153. Id. of Crustaceans. — Id. of Worms. — The three Orders of Crusta- 

 ceans, and characteristics of Decapods, and examples. — Id. of Tetradecapods. 

 — Id. of Entomostracans. — 154. Id. of Trilobites. 



VII. Animal Kingdom ; Vegetable Kingdom. — Page 155. The three sub- 

 divisions of Ordinary Mollusks. — Their characteristics, with examples. — Pecu- 

 liarities of the Cephalopods. — 156. Peculiarities of the two groups of Cepha- 

 lates. — 157. Name of the group of Acephals, and peculiarities. — The three 

 groups of Anthoid Mollusks. — Peculiarities of Bryozoans. — 158. Distinctions 

 between Brachiopods and Conchifers or the ordinary Bivalves. — The three 

 Classes of Radiates. — Characteristics of Echinoderms. — Id. of Acalephs. — Id. 

 of Polyps. — 159. Distinctions of Crinoids and other Echinoderms. — 161. Dis- 

 tinctions of the two groups of Crinoids, the Crinideans and Cystideans. — 162. 

 Coral -making Acalephs. — 163. The two Orders of Polyps. — Formation of Coral. 

 — Characteristics of Rhizopods. — 165. Id. of Sponges. — 165, 166. Two grand 

 divisions of plants. — Algas or sea-weeds. — Three subdivisions of Phsenogams. — 

 Characteristics of Gymnosperms, with examples. — Id. of Angiosperms, with 

 examples. — Id. of Endogens. 



VIII. Palaeozoic Time, Silurian Age, Potsdam Period. — Page 167. First 

 of the Palaeozoic Ages. — Origin of the term Silurian. — 167. Names of the three 

 Periods in the American Lower Silurian, beginning with the earliest. — 168. Id. 

 in the Upper Silurian. — 171. The two Epochs of the Potsdam Period. — 172. 



