55 2 THE POPULAR SCIENCE MONTHLY. 



guasres ; and the third was the " Flora Fossilis Helvetia " in one vol- 

 ume, with seventy plates. He passed the winter of 1854-'55 in Ma- 

 deira, on account of his health, and on his return from there published 

 a paper on the fossil plants of that island, and another on the probable 

 origin of the existing flora and fauna of the Azores, Madeira, and the 

 Canaries. In this paper, and in a work published in 1860 on tertiary 

 climates in their relation to vegetation, as well as in parts of his larger 

 works on Switzerland, he propounded his theory of the existence of 

 the Continent of Atlantis, during the Miocene period ; a theory to 

 which he held steadfastly for many years, but which the later sound- 

 ings have shown to be extremely improbable in fact, and his own re- 

 searches to be not needed to account for the phenomena of the dis- 

 tribution of plants and animals over the earth. 



In 1 862 Heer examined the fossil flora of the lignites of Bovey- 

 Tracy in Devonshire, and published a memoir upon them in the 

 " Philosophical Transactions." At about the same time, he published 

 a paper in the " Journal of the Geological Society " on certain fossil 

 plants of the Isle of Wight. As his fame grew, fossils were sent to 

 him in masses to be examined from all parts of the world ; and we 

 find among his papers notes on the cretaceous phyllites of Nebraska, 

 the floras of Moletein in Moravia, Ruedlinburg in Germany, the Bal- 

 tic miocene of Prussia, of the lignites of Zselythales in Hungary, of 

 Ando in Norway, and " Contributions to the Fossil Flora of Portugal." 

 All of these works, important as they were in themselves, were only 

 leading up to the great work of his life the investigation of the Arc- 

 tic fossil flora and the deduction from it of a satisfactory theory of the 

 distribution of life over the earth. According to Dr. Gray, his first 

 essay in this domain which he has made so peculiarly his own was in 

 a paper on certain fossil plants of Vancouver Island and British Colum- 

 bia, published in 1865 ; and in 1868 he brought out the first of the 

 series of memoirs upon the ancient floras of Arctic America, Green- 

 land, Spitzbergen, Nova Zembla, Arctic and Subarctic Asia, etc., 

 which together make up the seven quarto volumes of the "Flora 

 Fossilis Arctica," the last of which was finished only a few months 

 before his death. According to M. de Saporta, he had been struck 

 with the importance of the American element in what he called the 

 Molassic flora of Switzerland. There was no question in it of vague 

 analogies, but a number of dominant and characteristic species were 

 represented by "homologues" or directly corresponding kinds now 

 peculiar to North America, while there was nothing like them in Eu- 

 rope or the whole Eastern Continent, except as fossils. Among these 

 plants were the sequoia of California, the cypress of Louisiana, the 

 parasol palm of the Antilles, the tulip-tree, maples, and poplars, the 

 European fossil forms of which were as like them as if they had been 

 shaped upon living American trees as models. He saw in these re- 

 semblances, which implied that identical species were at some time in 



