Trigonocarpum 136 Sternbergia 137 Walchia imbricatula 138 Foliage of the Jurassic Period 177 Podozamites 178 Salisburia 180 Sequoia 181 Populus primæva 191 Stercalia and Laurophyllum 194 Vegetation of the Cretaceous Period 195 Platanus 198 Protophyllum 199 Magnolia 200 Liriodendron (two Figures) 201 Brasenia 207 Gaylussaccia resinosa 228 Populus balsamifera 229 Fucus 230 THE GEOLOGICAL HISTORY OF PLANTS. CHAPTER I. PRELIMINARY IDEAS OF GEOLOGICAL CHRONOLOGY AND OF THE CLASSIFICATION OF PLANTS. The knowledge of fossil plants and of the history of the vegetable kingdom has, until recently, been so fragmentary that it seemed hopeless to attempt a detailed treatment of the subject of this little book. Our stores of knowledge have, however, been rapidly accumulating in recent years, and we have now arrived at a stage when every new discovery serves to render useful and intelligible a vast number of facts previously fragmentary and of uncertain import. The writer of this work, born in a district rich in fossil plants, began to collect and work at these as a boy, in connection with botanical and geological pursuits. He has thus been engaged in the study of fossil plants for nearly half a century, and, while he has published much on the subject, has endeavoured carefully to keep within the sphere of ascertained facts, and has made it a specialty to collect, as far as possible, what has been published by others. He has also enjoyed opportunities of correspondence or personal intercourse with most of the more eminent workers in the subject. Now, in the evening of his days, he thinks it right to endeavour to place before the world a summary of facts and of his own matured conclusions--feeling, however, that nothing can be final in this matter; and that he can only hope to sketch the present aspect of the subject, and to point the way to new developments, which must go on long after he shall have passed away.