Yol.  49.] 
NUFENENSTOCK  (lePONTINE  ALPS). 
93 
matter  belongs  to  a  different  part  of  the  map,  I  may  mention  that 
we  failed  to  discover,  after  a  careful  search,  the  black-garnet  schist 
on  the  eastern  side  of  the  Furka  Pass,  all  being  Jurassic  rock  at 
that  locality. 
It  must  be  remembered  that  Dr.  von  Fritsch’s  map  was  made  before 
the  microscope  was  generally  employed  in  petrology.  Without  that 
instrument,  and  the  training  which  it  gives,  the  black-garnet  schist 
and  the  ‘spotted’  Jurassic  may  be  easily  confused.  In  the  field, 
even  now,  difficulties  occasionally  arise,  and  the  geologist  is  com¬ 
pelled  to  work  round  about  a  particular  outcrop  in  search  of  rocks 
in  better  preservation,  before  he  can  make  up  his  mind.1  So  that, 
while  expressing  these  differences  of  opinion  on  some  points  of 
detail,  I  cannot  conclude  without  expressing  my  sense  of  the  high 
value  of  Dr.  von  Fritsch’s  map.  Those  who  know  the  region  well 
can  best  appreciate  the  untiring  patience  and  labour  which  that 
author  has  devoted  to  a  very  difficult  task. 
1  For  instance,  I  am  now  not  quite  satisfied  about  the  nature  of  the  actual 
summit  of  the  peak,  the  specimen  brought  therefrom  proving  to  be  a  little 
abnormal. 
