PART II

§§ iv. and v. On the evidence from Geology. (The reasons for combining the two sections are given in the Introduction) 22 § vi. Geographical distribution 29 § vii. Affinities and classification 35 § viii. Unity of type in the great classes 38 § ix. Abortive organs 45 § x. Recapitulation and conclusion 48

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ESSAY OF 1844