VI PREFACE 



notion of the beauties of the swamp" brilliantly coloured 

 Newts engaged in amorous play, concert-giving Frogs, and meta- 

 morphosing Tadpoles. The motto assigned to the Eeptiles seems 

 singularly appropriate when we consider that poisonous snakes 

 have been developed from harmless forms, and that many kinds 

 of reptiles have lost limbs, teeth, and eyesight in the process 

 of evolution. 



The present work is intended to appeal to two kinds of 

 readers to the field-naturalist, who, while interested in life- 

 histories, habits, and geographical distribution, beauty or strange- 

 ness of forms, is indifferent to the homologies of the metasternum 

 or similar questions ; and to the morphologist, who in his turn 

 is liable to forget that his specimens were once alive. 



A great portion of the book is anatomical and systematic. 

 It was necessary to treat anatomy, especially that of the skeleton, 

 somewhat fully, since it has long been recognised that it is 

 impossible to base a scientific classification upon external 

 characters. The reader familiar with Vertebrate anatomy has a 

 right to expect that questions of special morphological interest 

 will be dwelt upon at length. Those who have no anatomical 

 foundation must be referred to one of the now numerous intro- 

 ductory manuals on the subject. 



The account of the Amphibia is more complete than that of 

 the Reptilia. It was possible to diagnose practically all the 

 recent genera ; and this has been especially done in the Anura, 

 in order to show how in an otherwise very homogeneous group 

 almost any part of the body, internal or external, can be modified 

 in kaleidoscopic variety. The same could not be done with the 

 Eeptilia. Their principal groups, called sub -classes in the 

 present work, in order to emphasise their taxonomic importance 

 in comparison with the main groups of Birds and Mammals, 

 differ so much from each other that it was decided to refrain 



