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Show Vlll CONTENTS. ON THE IMPERFECTION OF THE GEOLOGICAL RECORD. On the absence of intermediate varieties at the present day- On tbe nature of extinct intermediate varieties ; on their numberOn the vast lapse of time, as inferred from the rate of deposition and of denudation - On the poorness of our palreontological collections - On the intermittence of geological formations - On the absence of intermediate varieties in any one formation -On the sudden appearance of groups of species - On their sudden appearance in the lowest known fossil~ferous strata Page 279-311 CHAPTER X. ON THE GEoLOGICAL SuccESSION OF ORGANIC BEINGS. On the slow and successive appearance of new species- On their different rates of change- Species once lost do not reappear - Groups of species follow the same general rules in their appearance ancl disappearance as do single species -On ExtinctionOn simultaneous changes in the forms of life throughout the world- On the affinities of extinct species to each other and to living species- On the state of development of ancient formsOn the succession of the same types within the same areasSummary of preceding and present chapters . . 312-345 CHAPTER XI. GEOGRAPHICAL DISTRIBUTION. Present distribution cannot be accounted for by differences in physical conditions- Importance of barriers- Affinity of the productions of the same continent- Centres of creation- Means of dispersal, by changes of climate and of the level of the land, and by occasional means- Dispersal during the Glacial period co-extensive with the world . . • . 346-382 CONTENTS. lX CI-IAPTER XII. GEOGRAPHICAL DISTRIBUTION-continued. Distribut~o~ of fresh-water productions- On the inhabitants of oceamc Islands- Absence of Batrachians and of terrestrial Mammals- On the relation of the inhabitants of islands to those of th.e nearest mainland- On colonisation from the nearest source With subsequent modification- Summary of the last and present chapters Page 383-410 CHAPTER XIII. MUTUAL AFFINITIES OF ORGANIC BEINGS: MORPHOLOGY: EMBRYOLOGY: RuDIMENTARY ORGANS. CLASSIFICATION~ grou~s s~bordinate to groups-Natural system_ Rules an~ drfficul~1es 1? classification,.explained on the theory of descent w1th modrficatwn- Classification of varieties- Descent always ~s.ed in classification- Analogical or adaptive characters - Affimt1es, general, complex and radiating- Extinction separates and defines groups- MoRPHOLOGY, between members of the same class, between parts of the same individualEMBRYOLOGY, laws of, explained by variations not superveninoat an early age, and being inherited at a correspondino- ao-~ -RuDIMENTARY ORGANs ; their origin explained- Summ 0 ary b 411-458 CHAPTER XIV. RECAPITULATION AND CONCLUSION. Recapitulation of the difficulties on the theory of Natural Selection -Recapitulation of the general ancl special circumstances in its favo~r- Causes of the general belief in the immutability of spemes-How far the theory of natural selection may be e~tended- Effects of its adoption on the study of Natural history- Concluding remarks . . 459-490 INDEX •• 491 b |