the    Bone    bed,    there    are    certain     thin     bands    in
Gloucestershire,  named  by  the  Eev.  P.  B.  Brodie,  who

1  For  notices  of  this  old  land,  see  De  la  Beche  '  On  the  Formation
of  the  Kocks  of  South  Wales  and  South- West  of  England ' ;  and
Ramsay,  '  Denudation  of  South  Wales  and  the  Adjacent  Counties  of
England,'  Mem.  Geol.  Surv.  vol.  i.  1846;  and  'Abnormal  Conditions
of  Secondary  Deposits,'  &c.,  by  Charles  Moore,  '  Quarterly  Journal
Geol.  Soc.'  vol.  xxiii.,  1867.
M  2


164  Physical  Geography.
first  described  them,  the  '  insect  limestones.'  The
fossilised  contents  of  these  bands  throw  some  light  on
the  physical  geography  of  the  lands  that  bordered  the
waters  of  the  time,  for  in  them  have  been  found
numerous  elytra  and  other  remains  of  Beetles,  Grass-
hoppers, Cicadas,  Dragon-flies,  and  other  neuropterous
insects,  associated  with  a  fresh-water  shell  of  the  genus
Cyclas,  the  shells  of  Cypris,  and  with  ferns,  Cycads,
and  leaves  of  Monocotyledonous  plants.  These  beds,
therefore,  indicate  either  fresh-water  strata,  or  else  the
immediate  proximity  of  land,  from  whence  streams
washed  into  the  sea  insects,  fresh-water  Crustacea,
shells,  and  land  plants.
