5°4 



NATURE 



[October 12, 191 1 



is widely spread in the warmer regions of both the Old 

 and New World. Gleichenia may, as a rule, be easily 

 recognised by the regular forked branching of the fronds, 

 as also by the structure of its spore-capsules and by the 

 anatomy of its stem. Fragments of fronds hardly dis- 

 tinguishable from those of some surviving species have 

 been found in Upper Jurassic rocks on the Sutherland 

 coast and in YVealden strata on the Continent. In rocks 

 of Wealden age near Brussels, pieces of stems have been 

 discovered by Prof. Bommer sufficiently well preserved to 

 be submitted to microscopic examination, and showing 

 anatomical features exactly like those of the living species. 

 The occurrence of numerous Gleichenia fronds in sedi- 

 mentary rocks of Lower Cretaceous age near the edge of 

 the Greenland ice-sheet on Disco Island, in lat. 70 N., 

 points to climatic conditions very different from those 

 which now prevail. This is one of many instances re- 

 vealed by a study of ancient floras of remarkable changes 

 in geographical distribution as in climate. Gleichenia, 

 like many other plants which have long ceased to exist 

 in Europe, was formerly a common northern genus, and 

 may have had its origin in the far north, whence it was 

 driven by adverse conditions to seek a home in more 

 congenial surroundings. 



The fern genus Matonia is now represented bv two 

 species in the Malay region ; one of them was discovered 

 a few years ago by Mr. Hose in a locality in Borneo, and 

 has not been found elsewhere ; the other and better known 

 species, Matonia pectinata, occurs in the Malay Peninsula 

 and on the mountains of Borneo. It is a fern with a creep- 

 ing stem, from which are given off large spreading fronds 

 borne on slender stalks reaching a height of 6 to S feet. 

 It is recognised by the shape of the leaf and by other 

 more important characters, notably by the structure of 

 its stem, in which it differs from all other members of 

 the fern class. 



Its isolated position among the ferns and its limited 

 geographical range are in themselves suggestive of 

 antiquity. The records of the rocks abundantly confirm 

 this inference. Fossil fern leaves closely resembling those 

 of Matonia pectinata occur in strata of Rhaetic age in 

 Germany and in other parts of the world. In England 

 this type has been found in the Jurassic beds on the 

 Yorkshire coast and in Wealden strata not far from 

 Hastings. From Wealden rocks in Belgium pieces of 

 stems have been obtained exhibiting anatomical features 

 identical with those of the recent species. Fronds prac- 

 tically identical with those of the Malayan fern are re- 

 corded from an Austrian locality from rocks higher in the 

 Cretaceous series, but no satisfactory evidence is available 

 of the persistence of the Matonia family in Europe or in 

 the northern hemisphere during the latest phase of the 

 Cretaceous or throughout the whole of the Tertiary period. 

 The existing species of Matonia are the last survivors of 

 a family which once flourished over a wide area in Europe 

 and extended to the other side of the Atlantic. Exposed 

 to unfavourable climatic conditions, and possibly affected 

 by the revolution in the plant-world consequent on the 

 appearance of the flowering plants, Matonia gradually re- 

 treated across the equator until this " living fossil " found 

 a last retreat in Malaya, the home of not a few links with 

 a remote past. 



Brief reference may be made to another fern, the genus 

 Dipteris, which grows in association with Matonia on 

 Mt. Ophir and elsewhere in the Malay Peninsula. Dipteris 

 is represented by more species and has a wider geo- 

 graphical range than Matonia ; it occurs in northern India, 

 central China, in New Caledonia, and other islands. The 

 fronds are distinguished bv their long, deeply cut seg- 

 ments, spreading from the top of a -lender stalk. In the 

 Rhjctic plant-beds nf northern and central Europe, North 

 America, Tonkin, and elsewhere, numerous fossil leaves 

 have been discovered which bear a close resemblance to 

 existing species of Dipteris. Similar fronds have been 

 found in the Jurassic rocks on the Yorkshire coast and in 

 Sutherland. It is impossible to sav with confidence how 

 nearly these Jurassic ferns are related to the existing 

 species, bul there can be no reasonable doubt that Dipteris, 

 like Matonia, is a fern which connects the present with 

 a past too far off to be measured by ordinary standards 

 of time. 



NO. 2l8g, v O L - 87] 



The large class of plants known as the conifers — though 

 the name- is in certain cases a misnomer, as some members 

 bear no cones — including the pines, larches, firs, and 

 several other trees, has a very much longer past history 

 than the flowering plants. In rocks of all ages down to 

 the Upper Pateozoic strata the remains of leafy shoots, 

 pieces of petrified wood, seeds, and cones are abundant 

 fossils, but the difficulty is to piece together the disjecta 

 membra and to determine the degree of relationship 

 between the extinct and the living. 



1 will confine myself to two genera of conifers which 

 are especially noteworthy as persistent types — plants, like 

 the fern Matonia, which formerly played a much more 

 conspicuous rdle in the world's vegetation than they do 

 now. Everyone is familiar with the Californian trees 

 known as Sequoia or Wellingtonia. 



The redwood, Sequoia sempervirens, occupies a narrow 

 belt of country, rarely more than twenty or thirty miles 

 from the coast, 300 miles long from Monterey in the south 

 to the frontiers of Oregon. The tapering trunk, rising to 

 a height of more than 300 feet, gives off short horizontal 

 branches thickly set with narrow leaves dispersed in two 

 ranks, as in the yew. The female flowers have the form 

 of oblong cones from three-quarters to one inch long, and 

 each woody cone-scale bears several small seeds on its 

 upper surface. The second and more familiar species, 

 S. gigantea, the mammoth tree, which is commonly culti- 

 vated in this country, has an even more restricted range, 

 being confined to groves on the western slopes of the 

 Sierra Nevada between 3000 to 9000 feet above sea-level. 

 This species is at once distinguished from the redwood by 

 iis stiff, sharply pointed and scale-like leaves, and by its 

 rather larger cones. 



In the British Museum there is a section of a mammoth 

 tree which shows on its polished surface 1335 rings of 

 growth. On the assumption that each ring marks a year's 

 growth, the tree when felled in 1890 was 1335 years old, 

 and when Charles the Great was crowned Emperor at 

 Rome it had already flourished for more than 200 years. 

 These two giant conifers, remarkable as being probably the 

 tallest trees in the world, become even more impressive 

 when we know something of their past. The investiga- 

 tion of the herbaria buried in the earth's crust reveals the 

 occurrence of similar, and in some cases apparently 

 identical, species in many parts of Europe and in American 

 localities far from their present home. It has been demon- 

 strated that the big trees of California are the survivors 

 of a once vigorous family which formerly flourished in 

 many parts of the Old World, but as the result of altered 

 circumstances, changed physical conditions, or unequal 

 competition with other types in the struggle for life, 

 dwindled in numbers and narrowly escaped extinction. 



At Bovey Tracey in Devonshire there is a basin-shaped 

 depression in the granitic rocks of Dartmoor filled with 

 clay, gravel, and sand — the flood-deposits of a Tertiary 

 lake containing the waifs and strays of the vegetation 

 from the surrounding hills. Among the commonest plants 

 is one to which the late Oswald Heer gave the name 

 Sequoia Couttsiae, and his reference of the specimens to 

 Sequoia has recently been confirmed by the researches of 

 Mr. and Mrs. Clement Reid. This Tertiary species is 

 represented by slender twigs almost identical with those 

 of S. gigantea and by well-preserved cone-scales and seeds. 

 Moreover, it has been possible to examine microscopically 

 the carbonised outer skin of the leaves, and to demonstrate 

 its close agreement with that of the superficial tissue in 

 the leaves of the Californian tree. With the Bovey Tracey 

 Sequoia are associated fragments of Magnolia, Vitis, the 

 swamp cypress of North America, as well as other types 

 which have long ceased to exist in the British Isles. 

 Twirls and cones identified as those of Sequoia are re- 

 corded from several continental districts from both 

 Cretaceous and Tertiary strata. The genus occurs in 

 abundance in Tertiary beds on Disrn Island and in Spits- 

 bergen. Dr. Nathorst has obtained specimens from the 

 Arctic EHesmere Land almost as perfect as herbarium 

 specimens. Remains of Sequoia have been found also in 

 Tertiary rorl;= on the banks of the Mackenzie River, in 

 Alaska, Saghalien Island, Vancouver Island, and else- 

 where. 



One of the most remarkable instances of the preserva- 



