[152] Conjectured to be the wild stock of Bos grunniens.
[153] Recollections of a Journey through Tartary, Thibet, and China (ch. xv. p. 234), by M. Huc. Longman, 1852.
[154] For an account of the more modern changes of the tertiary fauna and flora of the British Isles and adjoining countries, and particularly those facts which relate to the "glacial epoch," see an admirable essay by Prof. E. Forbes. Memoirs of Geol. Survey of Great Brit. vol. i. p. 336. London, 1846. To this important memoir I shall have frequent occasion to refer in the sequel.
[155] See a paper by Charles J. F. Bunbury, Esq., Journ. of Geol. Soc., London, No. 6, p. 88. 1846.
[156] The Calamites were formerly regarded by Adolphe Brongniart as belonging to the tribe of Equisetaceæ; but he is now inclined to refer them to the class of gymnogens, or gymnospermous exogens, which includes the Coniferæ and Cycadeæ. Lepidodendron appears to have been either a gigantic form of the lycopodium tribe, or, as Dr. Lindley thinks, intermediate between the lycopodia and the fir tribe. The Sigillariæ were formerly supposed by Ad. Brongniart, to be arborescent ferns; but the discovery of their internal structure, and of their leaves, has since proved that they have no real affinity to ferns. According to the view now taken of their structure, their nearest allies in the recent world are the genera Cycas and Zamia; while Corda, on the other hand, maintains that they were closely related to the succulent euphorbias. Stigmaria is now generally admitted to have been merely the root of sigillaria. The scalariform vessels of these two genera are not conclusive in proving them to have a real affinity with ferns, as Mr. Brown has discovered the same structure of vessels in Myzodendron, a genus allied to the mistletoe; and Corda has lately shown that in two species of Stigmaria, hardly distinguishable by external characters, the vessels of the one are scalariform, and of the other dotted.
[157] Mr. Lindley endeavored formerly (1834) to show, in the "Fossil Flora," that Trigonocarpum Noeggerathii, a fruit found in the coal measures, has the true structure of a palm-fruit; but Ad. Brongniart has since inclined to regard it as cycadeous; nor is the French botanist satisfied that some specimens of supposed palm wood from the coal-mines of Radnitz in Bohemia, described by Corda, really belong to palms. On the other hand, Corda has proved Flabellaria borassifolia of Sternberg to be an exogenous plant, and Brongniart contends that it was allied to the Cycadeæ. See Tableau des Genres de Végétaux Fossiles. Paris, 1849.
[158] Prodrome d'une Hist. des Végét. Foss. p. 179. See also a late paper, Quart. Journ. of Geol. Soc. London, 1846, in which coal-plants of Alabama, lat. 33° N., collected by the author, are identified by Mr. Bunbury with British fossil species, showing the great southern extension of this flora.
[159] König, Journ. of Sci., vol. xv. p. 20. Mr. König informs me that he no longer believes any of these fossils to be tree ferns, as he at first stated, but that they agree generically with plants in our English coal-beds. The Melville Island specimens, now in the British Museum, are very obscure impressions.
[160] Fossil Flora of Great Britain, by John Lindley and William Hutton, Esqrs., No. IV.
[161] Fossil Flora of Great Britain, by John Lindley and William Hutton, Esqrs. No. IV.