Of the nature of that law by which the extinction of a race of highly organized beings is determined, and whose effects through innumerable ages palæontology has in part revealed, we are as utterly ignorant as of that which governs the first appearance of the minutest living animalcule which the powers of the microscope enable us to descry; both are veiled in inscrutable mystery, the results only are within the scope of our finite comprehension.[3] [Footnote 3: See the concluding part of Lecture VIII. § 46, Wonders of Geology, vol. ii. p. 890.] INTRODUCTION. The publication of Mr. Parkinson's "_Organic Remains of a former World_," at the commencement of the present century, must be regarded as a memorable event in the history of British Palæontology: it was the first attempt to give a familiar and scientific account of the fossil relics of animals and plants, accompanied by figures of the specimens described. The three volumes[4] of which the work consisted, appeared at considerable intervals; the last was published in 1811. Although nearly forty years have since elapsed, and hundreds of geological works, of all kinds and degrees of merit, have subsequently been issued, Mr. Parkinson's Plates, owing to their fidelity and beauty, are still in such request, as to induce the proprietor, Mr. Bohn, now that the work is out of print, to publish them, with the descriptions and modern names of the fossils represented. [Footnote 4: Three volumes, in 4to.; price 10_l._ 10_s._] I have added a few explanatory remarks, and in the "Supplementary Notes," have given extended notices of some of the most interesting subjects, with the view of rendering the volume more intelligible and acceptable to the general reader.