CONTENTS. IX 



CHAPTEE XII. 



Geographical Distribution — continued. 



Distribution of fresh-water productions — On the inhabitants of 

 oceanic islands — Absence of Batrachians and of terrestrial Mam- 

 mals — On the relation of the inhabitants of islands to those of 

 the nearest mainland — On colonisation from the nearest source 

 with subsequent modification — Summary of the last and pre- 

 sent chapters Page 383-410 



CHAPTEE XIII. 



Mutual Affinities of Organic Beings : Morphology : 

 Embryology : Rudimentary Organs. 



Classification, groups subordinate to groups — Natural system — 

 Bules and difficulties in classification, explained on the theory of 

 descent 'with modification — Classification of varieties — Descent 

 always used in classification — Analogical or adaptive characters 



— Affinities, general, complex and radiating — Extinction se- 

 parates and defines groups — Morphology, between members 

 of the same class, between parts of the same individual — 

 Embryology, laws of, explained by variations not supervening 

 at an early age, and being inherited at a corresponding age 



— Rudimentary organs ; their origin explained — Summary 



411-458 



CHAPTEE XIV. 



Recapitulation and Conclusion. 



Recapitulation of the difficulties on the theory of Natural Selection 



— Recapitulation of the general and special circumstances in its 

 favour — Caifses of the general belief in the immutability of 

 species — How far the theory of natural selection may be 

 extended — Effects of its adoption on the study of Natural 

 history — Concluding remarks 459-490 



Index 491 



