The last district which it is at all necessary for me to mention here, is that of the GALAPAGOS ARCHIPELAGO, situated under the Equator, and between five and six hundred miles West of the coast of America. These islands are entirely volcanic in their composition; and on two of them the volcanic forces have within late years been seen in activity. There are five principal islands, and several smaller ones: they cover a space of 2° 10′ in latitude, and 2° 35′ in longitude. The climate, for an equatorial region, is far from being excessively hot: it is extremely dry; and although the sky is often clouded, rain seldom falls, excepting during one short season, and then its quantity is variable. Hence, in the lower part of these islands, even the more ancient streams of lava (the recent ones still remaining naked and glossy) are clothed only with thin and nearly leafless bushes. At an elevation of 1200 feet, and upwards, the land receives the moisture condensed from the clouds, which are drifted by the trade wind over this part of the ocean at an inconsiderable height. In consequence of this, the upper and central part of each island supports a green and thriving vegetation; but from some cause, not very easily explained, it is much less frequented, than the lower and rocky districts are, by the feathered inhabitants of this archipelago. By a reference to the localities here described, it is hoped that the reader will obtain some general idea of the nature of the different countries inhabited by the several animals, which will be described in the following sheets. The vertebrate animals in my collection have been presented to the following museums:—the Mammalia and Birds to the Zoological Society; the Fishes to the Cambridge Philosophical Society; and the Reptiles, when described, will be deposited in the British Museum. For the care and preservation of all these and other specimens, during the long interval of time between their arrival in this country and my return, I am deeply indebted to the kindness of the Rev. Professor Henslow of Cambridge. With respect to the gentlemen, who have undertaken the several departments of this publication, I hope they will permit me here to express the great personal obligation which I feel towards them, and likewise my admiration at the disinterested zeal which has induced them thus to bestow their time and talents for the good of Science. LIST OF PLATES. Plate I. Desmodus D’Orbignyi. II. Phyllostoma Grayi. III. Vespertilio Chiloensis. IV. Canis antarcticus. V. —— Magellanicus. VI. —— fulvipes. VII. —— Azaræ. VIII. Felis Yagouaroundi. IX. —— Pajeros. X. Delphinus Fitz-Royi. XI. Mus longicaudatus. —— gracilipes. XII. —— elegans. —— bimaculatus. XIII. —— flavescens. —— arenicola. XIV. —— Magellanicus. —— brachiotis. XV. —— Renggeri.