THE 
QUARTERLY 
JOURNAL 
OF  THE 
GEOLOGICAL  SOCIETY  OE  LOXDOX. 
EDITED  BY 
THE  ASSISTANT -SECRETARY  OF  THE  GEOLOGICAL  SOCIETY. 
Quod  si  cui  mortalium  cordi  et  curse  sit  non  tantum  inventis  haerere,  atque  iis  uti,  sed  ad  ulteriora 
penetrare;  atquenon  disputando  adversarium,  sed  opere  naturam  vincere ;  denique  non  belle  et  probaLiliter 
opinari,  sed  certo  et  ostensive  scire;  tales,  tanquam  veri  scientiarum filli,  nobis  'si  videbitur)  se  adjungant. 
— Novum  Organum,  Prcefatio. 
VOLUME  THE  FORTY-NINTH. 
1893. 
LONDON : 
LONGMANS,  GREEN,  AND  CO. 
PARIS:  FRIED.  KLINCKSIECK,  11  RUE  DE  LILLE;  F.  SAVY,  77  BOULEVARD  ST.  GERMAIN; 
LEIPZIG:  T.  O.  WEIGEL. 
SOLD  ALSO  AT  THE  APARTMENTS  OF  THE  SOCIETY. 
MDCCCXCIII. 
