252 INDEX. 



PAGE 



Future life- periods, probable aspects of, . . .174 



Future vitality, man's influence on, .... 232 



Galerites, characteristic chalk sea-urchin, figured, . . 145 



Generation, spontaneous, unsatisfactory evidence of, . .181 



Geological classification systems and periods, . . .73 



Geology, her own proper field of inquiry, . . . 245 



Geology, spirit in which to study, .... 244 



Geology, the vital problems yet to solve, ... 75 



Glacial action, appearances of, during Old Red era, . . 91 



Glacial or Northern Drift epoch, ..... 1(55 

 Glyptodon, extinct gigantic armadillo, .... 163 

 Goniaster (corner-star), chalk star-fish, figured, . . . 145 



Goniatite, carboniferous cephalopod, figured, . . . 109 



Graptolites, Silurian zoophytes, figured, .... 86 



Gryphsea, characteristic shell of the Oolite, . . .134 



Gymnogens, their aspect and function, . . . .42 



Gyracanthus, carboniferous fin-spine, figured, . . . Ill 



Hamites, characteristic chalk cephalopod, . . .347 



Hemipneustes, sea-urchin of Cretaceous epoch, figured, . . 145 



Higher and lower, as applied to organised beings, . . 55 



Hippurites, characteristic cretaceous bivalve, . . .146 



Homology, the anatomical doctrine of, . . .53 



Human race, mutability of, . , . . .173 



Human race, probable antiquity of, . . 215 



Human race, probable duration of, .... 230 



HylaBosaurus, great land saurian of the Weald, . . . 138 



Hypotheses, their value in science, . . . .178 



Hypozoic or metamorphic strata, ..... 81 







Ice-action, appearances of, during Devonian period, . . 91 



Ice-action, supposed occurrence of, in Permian, . . . 115 



Ichnites, or fossil footprints, how occurring, . . 1 26 



Ichnology, or science of fossil footprints, . . . .126 



Ichthyosaurus, oolitic marine reptile, figured, . . . 137 



Igneous or fire-formed rocks, defined, . . 69 



Immortality of life-forms, question of, . 206 



Implements, flint, what they indicate, . . . .217 



Inoceramus, cretaceous species of, figured, . . . 146 



Inquiry, spirit of, necessary for geology, . . . 244 



Insects, various genera, fossil in oolite, .... 133 

 Irish gigantic deer, sketch of, figured, .... 169 



Labyrinthodon, lower secondary reptile, figured, . . 125 



Lamarckian hypothesis of vital development, . . . 197 



Law, natural, its nature and importance, . . % 242 



Law of similar habit and economy, .... 199 



