Yol.  49.]  ILkBIOLABIAX  CHEBT  FBOM  HTJLLIOX  I5LAXD.  219 
volcanic  complex  at  the  Lizard ;  but  if  the  last-named  rocks  belonged 
to  one,  then  there  were  two  complexes  of  different  dates. 
As  regards  the  case  of  the  granitoid  rock  and  the  serpentine, 
sonth  of  the  Lion  Hock :  difficulties  were  caused  in  this  district  by 
the  fact  that  there  was  an  intrusive  granite,  which  sometimes 
brought  up  fragments  of  an  older  dark  rock,  and  a  granulitic  rock, 
included  as  large  fragments  in  the  serpentine,  and  the  two  were 
often  very  like  one  another.  Without  examining  on  the  ground 
the  instance  described  by  the  Authors,  he  was  not  prepared  to  say 
to  which  of  these  rocks  he  should  attribute  it ;  going  by  the 
diagram,  there  were  difficulties  in  either  reference.  If  intrusive 
granite,  then  its  form  and  structure  were  very  strange  :  if  caught  up 
in  the  serpentine,  then  we  must  suppose  the  heat  of  the  latter  to 
have  produced  a  slight  plasticity. 
He  had  not  examined  the  particular  section  of  banded  schist  and 
serpentine  found  in  the  cliffs  near  Ogo  Dour,  and  it  was  doubtless  a 
puzzling  one.  But  that  the  Lizard  serpentine  at  several  places  was 
distinctly  intrusive  in  the  Hornblendic  or  the  Granulitic  Series,  he 
was  convinced — for  instance,  in  Ogo  Dour  Bay  (farther  north)r 
at  Henscarth,  Porthalla,  Kildown  Point,  etc.  Horeover,  he  had 
repeatedly  obtained  proofs  of  the  intrusive  nature  of  serpentine 
in  other  regions,  and  did  not  believe  the  same  rock  could  have  two 
modes  of  origin.  The  Horway  case  he  knew  as  a  rock,  and  believed 
it  was  only  a  ‘  sill  ’  made  schistose  by  pressure.  As  regards  the 
case  at  the  Lizard,  was  the  hornblende-rock  associated  with  the 
serpentine  the  normal  hornblende-schist  of  the  district '?  Of  this 
he  felt  doubts.  If  it  were,  we  might  have  only  a  peculiar  case  of 
intrusion ;  if  not  (as  he  suspected),  then  this  might  be  a  case  of 
fluxion-banding,  the  peridotic  magma  being  either  exceptionally  ill- 
mixed  with  a  more  felspathic  one  (cases  of  which  did  occur),  or 
possibly  having  locally  half-dissolved  some  fragments  of  hornblende- 
schist.  There  were  certainly  no  signs,  in  the  rocks  themselves, 
that  they  had  been  modified  by  pressure,  indications  of  which  at 
the  Lizard  were  only  local.  Banded  structures  caused  by  fluxional 
movements  in  igneous  rocks,  leading  sometimes  to  an  apparent 
stratification  of  material  with  considerable  differences,  were  now 
becoming  familiar.  To  some  of  these  the  speaker  referred.  The 
case  discussed  was  a  curious  and  interesting  one,  and  he  reserved  a 
final  opinion  till  he  had  seen  it  in  the  field ;  but  it  did  not  alter  his 
view  (for  he  agreed  with  Hr.  Hill's  remarks)  that  the  Lizard  ser¬ 
pentine  was  an  altered  peridotite,  intrusive  in  the  hornblendic  and 
granulitic  groups. 
Dr.  Hicxs  said  he  was  glad  that  there  were  some  reasons  for 
believing  that  the  radiolarian  chert  might  be  of  Ordovician  age  • 
and  he  hoped  that  this  important  discovery  would  lead  to  the 
detection  of  similar  bands  in  neighbouring  areas,  where  no  doubt 
could  arise  as  to  the  geological  horizon.  He  would  be  inclined  to 
place  the  beds  towards  the  base  of  the  Ordovician,  for  many  years 
ago  he  arrived  at  the  conclusion,  as  stated  in  papers  read  before 
the  Geological  Society  in  1875  and  1876,  that  the  Arenig  and 
