Transcriber's note: Text enclosed by underscores is in italics (_italics_). A single underscore introduces a subscript (CO_2), and a caret a superscript (B^1). Page numbers enclosed by curly braces (for example: {25}) have been incorporated to facilitate the use of the Alphabetical Index and other page references in the text. * * * * * THE CAMBRIDGE NATURAL HISTORY EDITED BY S. F. HARMER, Sc.D., F.R.S., Fellow of King's College, Cambridge; Superintendent of the University Museum of Zoology AND A. E. SHIPLEY, M.A., Fellow of Christ's College, Cambridge; University Lecturer on the Morphology of Invertebrates VOLUME VIII [Illustration] MACMILLAN AND CO., LIMITED LONDON . BOMBAY . CALCUTTA MELBOURNE THE MACMILLAN COMPANY NEW YORK . BOSTON . CHICAGO ATLANTA . SAN FRANCISCO THE MACMILLAN CO. OF CANADA, LTD. TORONTO _Frontispiece._ PHYSICAL FEATURES OF THE WORLD AFFECTING THE GEOGRAPHICAL DISTRIBUTION OF AMPHIBIA AND REPTILES. AMPHIBIA AND REPTILES By HANS GADOW, M.A. (Cantab.), Ph.D. (Jena), F.R.S., Strickland Curator and Lecturer on Advanced Morphology of Vertebrata in the University of Cambridge. MACMILLAN AND CO., LIMITED ST. MARTIN'S STREET, LONDON 1909 _First Edition 1901_ _Reprinted 1909_ {v}PREFACE Linnaeus had but a poor opinion of the Amphibia and their describers, or he would not have called the former "pessima tetraque animalia," nor would he have dismissed the latter with the terse remark: "Amphibiologi omnium paucissimi sunt nullique veri." That was, however, nearly 150 years ago; and at the present time there are fewer difficulties in writing a book on Amphibia and Reptiles. Those who care for the study of Amphibia and Reptiles–the Herpetologists, to give them their scientific title–have never been numerous; but most of them have been serious students. One reason for the fact that this branch of Natural History is not very popular, is a prejudice against creatures some of which are clammy and cold to the touch, and some of which may be poisonous. People who delight in keeping Newts or Frogs, Tortoises or Snakes, are, as a rule, considered eccentric. But in reality these cold-blooded creatures are of fascinating interest provided they are studied properly. The structure of animals is intimately connected with their life-habits; and this correlation is perhaps more apparent in Amphibia and Reptiles than in any other class. The anatomist who studies internal and external structure is as much struck with the almost endless variety in details as he who takes the trouble to observe the living animal in its native haunts, or at least under conditions not too unnatural. He will agree with V. von Scheffel's Toad "that those above seem to have no {vi}notion of the beauties of the swamp"–brilliantly coloured Newts engaged in amorous play, concert-giving Frogs, and metamorphosing Tadpoles. The motto assigned to the Reptiles seems singularly appropriate when we