viii INTRODUCTORY NOTICE. 



University Museum under the direction of the Linacre Professor, 

 Dr. Rolleston. To him and to Mr. Charles Robertson, Demon- 

 strator in Anatomy, it is a pleasure to be indebted for friendly 

 help, always ready and always effective. I must add a further 

 acknowledgment of the great assistance to myself and every 

 student of physical science which is freely given in the magnificent 

 library now attached to the Museum by the wise liberality of 

 the Radcliffe Trustees. 



1 hope the care taken by my friends Mr. Lowry and Mr. 

 Dewilde, in giving to rny drawings the permanent form of 

 expressive engraving, will prove as useful to the student as it has 

 been gratifying to myself. 



Though some years have been engaged in the preparation of 

 this volume, I cannot regret the delay of publication, since it 

 has enabled me to give a full account of that gigantic animal 

 the Ceteosaurus, whose bones, dug out of the oolite in the in- 

 terval, have been arranged in the University Museum, under 

 my direction, by the steady hands of my assistant, Henry 

 Caudel. 



I know no country of such moderate extent in which so large 

 a series of persistent marine life can be placed in sure co-ordination 

 with physical conditions of land and sea through so long a range 

 of continuous time. On this account it has been thought right 

 to offer some reflections on the succession of the forms of life, 

 which may help to a thoughtful consideration of modern * theories 

 of evolution,' and to examine with care the later effects of oceanic 

 and atmospheric vicissitudes on rising and falling land, in con- 

 nection with local changes of^climate and occupation of the region 

 by quadrupeds of many families older than the race of man. 



