IV PREFACE. 



of the Royal School of Mines, who has greatly relieved 

 me in the revision of proofs, and in other ways lightened my 

 share of the work. 



A fire at the printers^ has caused some delay in publication. 

 Having *' passed through the fire " almost unhurt, let us 

 hope that our success is assured — and that the Geological 

 Record may continue to carry out the motto of its publishers, 

 " Ale RE flammam/^ in a less literal way. 



WILLIAM WHITAKER. 



London, July 1877. 



