xviii INTRODUCTORY AND EXPLANATORY 



the Jurassic, when the Dinosaurs held carnival, 

 variously put at from 15,000,000 to 6,000,000 

 years; while from the beginning of the Eocene, 

 when the mammals began to gain the suprem- 

 acy, until now, the figures vary from 3,000,000 

 to 5,000,000 years. So the question of age will 

 be left for the reader to settle to his or her satis- 

 faction. 



The restorations of extinct animals may be 

 considered as giving as accurate representations 

 of these creatures as it is possible to make ; they 

 were either drawn by Mr. Knight, whose name 

 is guarantee that they are of the highest quality, 

 or by Mr. Gleeson, with the aid of Mr. Knighfs 

 criticism. That they are infallibly correct is out 

 of the question ; for, as Dr. Woodward writes 

 in the preface to " Extinct Monsters," " restora- 

 tions are ever liable to emendation, and the pres- 

 ent . . . will certainly prove no exception 

 to the rule." As a striking instance of this, it 

 was found necessary at the last moment to 

 change the figure of Hesperornis, the original 

 life-like portrait proving to be incorrect in 

 attitude, a fact that would have long escaped 

 detection but for the Pan-American Exposition. 



