12 



BRITISH EOCENE ELORA. 



of Greenland, and elsewliere, in beds of the same age ; the whole tending, perhaps, to 

 show that the existing genera of Coniferge were less completely diflFerentiated previous to 

 the Eocene time than has been generally supposed. For the Arctic Kome Heer claims 

 Pinus and Tsuga, and Pinus and Abies for Atane ; the leaves of Pinus Credneri are 

 described as lying in thousands on some of the slabs ; so that, even in Cretaceous times, 

 forests of needle-leaved Coniferae must have characterised northern latitudes. Pinus 

 and Sequoia are also described from the North-American Cretaceous of Dakota. 



In the Tertiaries the Gymnosperms are quite subordinate to the higher Phanerogams, yet 

 in 1878 Lesquereux estimated that no fewer than 225 species were known from them^ 



Of the three orders of Gymnosperms two are recognizable in British Tertiary rocks, 

 the Cycads being absent, and the Gnetaceae only met with in the London Clay of 

 Sheppey. Of the six orders of Coniferae all seem more or less certainly represented. 



Among the Cupressineae, there is Libocedrus fohage from Bromley and from the 

 London Clay perfect examples of fruits, apart from the doubtful species of Bowerbank, 

 belonging to a section of Callitris met with in Australia ; though only that now confined 

 to Africa occurs in Ettingshausen's list of Sheppey fruits. But there is no ground 

 for including Callitris or Cupressinites in the Alum-Bay flora. In the Tertiary swamp- 

 clay of Bournemouth there are in places innumerable detached twigs, which precisely 

 resemble those of Sequoia Couttsia at Bovey ; but the few cones associated with them are 

 distinctly Cupressineous. Types of Libocedrus and Thuya appear in the South of France 

 in the Oligocene, and the North-African Callitris is found in the Eocene of Aix. A 

 number of other Cupressineae have been described from fragments scarcely deserving 

 notice. Of the Taxodieae we appear to have representatives of Sequoia, Taxodium, and 

 perhaps Athrotaxis ; but those in the Alum-Bay list are probably Podocarps of a single 

 species. The Sequoia Bowerbankii of the Sheppey list by Ettingshausen, found only 

 at Herne Bay, and in which four species of Bowerbank's Petrophiloides had been 

 absorbed by Heer, is a cone of the Alder, and bears no resemblance to Sequoia. S. 

 Langsdorjii may occur at Mull and Antrim, but the foliage only is known, S. Coutfsics 

 from Bovey is one of the oldest Eocene forms ; and, unlike other species characteristic of 

 the European Tertiaries, was not dimorphic. The Arctic species confounded with S. 

 Couttsics is also found at Antrim. It is quite distinct, and might be fittingly named 

 after Mr. Whymper, who brought many specimens from Greenland. S. Sternbergi is, as 

 originally described, an Araucaria allied to A. Cunnhighami, but a distinct species of 

 Sequoia has since been confused with it. The Arctic Cretaceous Sequoias were evidently 

 polymorphous, and are divided into quite an unnecessary number of genera; as it is 

 palpable in some cases that more care or good fortune in collecting would have shown 

 that two or three supposed species grew on one branchlet. We have strong evidence 

 of Taxodium and its sub-genus Glyptostrobus in England, foliage from Bournemouth 

 belonging probably to the former as well as the latter. Both are represented in the 

 Oligocenes and Miocenes of Europe and of Greenland, and are valuable indications of 



