TRANSACTIONS OF SECTION E. 733 



Before the publication of the doctrine of the origin of species by variation 

 find natural selection, all reasoning on their distribution was in subordination to 

 the idea that these were permanent and special creations; just as, before it was 

 shown that species were often older than the islands and mountains they inhabited, 

 naturalists had to make their theories accord with the idea that all migration took 

 place under existing conditions of land and sea. Hitherto the modes of dispersion 

 of species, genera, and families, had been traced; but the origin of representative 

 species, genera, and families, remained an enigma ; ' these could be explained only 

 by the supposition that the localities where they occurred presented conditions so 

 similar that they favoured the creation of similar organisms, which failed to ac- 

 count for representation occurring in the far more numerous cases where there is 

 no discoverable similarity of physical conditions, and of their not occurring in places 

 where the conditions are similar. Now under the theory of modification of species 

 after migration and isolation, their representation in distant localities is only a ques- 

 tion of time and changed physical conditions. In fact, as Darwin well sums up, 

 alP the leading facts of distribution are clearly explicable under this theory; such 

 as the multiplication of new forms ; the importance of barriers in forming and 

 separating zoological and botanical provinces; the concentration of related species 

 in the same area ; the linking together under different latitudes of the inhabi- 

 tants of the plains and mountains, of the forests, marshes, and deserts, and the 

 linking of these with the extinct beings which formerly inhabited the same areas ; 

 and the fact of different forms of life occurring in areas having nearly the same 

 physical conditions. 



With the establishment of the doctrine of the orderly evolution of species 

 under known laws, I close this list of those recognised principles of the science of 

 geographical distribution, which must guide aU who enter upon its pursuit. As 

 Humboldt was its founder, and Forbes its reformer, so we must regard Darwin as 

 its latest and greatest lawgiver. With their example, and their conclusions to 

 guide, advance becomes possible whenever discovery opens new paths, or study 

 and reflection retraverse the old ones. 



And it was not long before palaeontology brought to the surface new data for 

 the study of the present and past physical geography of the globe. 



This was the discovery in Arctic latitudes of fossil plants whose existing 

 representatives are to be found only in warm temperate ones. To Arctic travel- 

 lers and voyagers this discovery is wholly due. Of these, I believe I am cor- 

 rect in saying that Sir John Eichardson was the earliest, for he, in the year 

 1848, when descending the McKenzie river to the Polar Sea in search of the 

 Franklin Expedition, found in lat. 65° N. beds of coal, besides shales, full of leaves 

 of forest-trees belonging to such genera as the maple, poplar, taxodium, oak, &c. 

 In the narrative of his journey,^ Richardson mentions these fossils and figures some 

 of them ; and in a subsequent work * he speaks of them as ' leaves of deciduous trees 

 belonging to genera which do not in the present day come so far north on the 

 American continent by ten or twelve degrees of latitude.' This discovery was 

 followed, in 1853, by the still more remarkable one, by Captain M'Clure and 

 Sir Alexander Armstrong (during another search for Sir John Franldin), of pine- 

 cones and acorns imbedded in the soil of Banksland, in lat. 75° N., at an elevation 



' The representation of species Forbes alludes to as ' an accident .... which 

 has hitherto not been accounted for.' — Mem. Gcol. Survey, vol. i. p. 351. 



"^ Of the many pre-Darwinian writers on distribution who advocated the Lamar- 

 kian doctrine of evolution, I am not aware of any who suggested that it would 

 explain the existence of representative species, or indeed any other of the pheno- 

 mena of distribution. Von Baer, however, in the very year of the publication 

 of the first edition of the Oriffin of Specien, expressed his conviction, chiefly grounded 

 on the laws of geographical distribution, that forms now specifically distinct have 

 ■descended from a single parent form. See Orirjiii of Species, e"d. 5. Historical 

 Sketch, p. 23. 



' Boat Voyage throvgh BujjeH's Land and in the Arctic Sea, vol. i. p. 186. 



* Polar Regio7is, p. 289. 



