Vol.  49.] 
ST.  CASSIAN  STRATA  IN  SOUTHERN  TYROL. 
31 
(About  the  1600-metre  contour)  reddish-brown  ferruginous 
marls,  and  black  earthy  beds,  containing  characteristic 
St.  Cassian  fossils  and,  in  especial  abundance,  various 
species  of  Cidaris. 
Marls  and  thin-bedded  limestones,  aragonite  and  gypsum- 
bands,  with  sometimes  large  geodes ;  very  good  speci¬ 
mens  of  corals  and  sponges  were  found, 
f  Hard  yellowish  limestone,  breaking  up  in  large  blocks ; 
on  the  weathered  surface  of  some  of  these,  lithoden- 
droid  corals  and  encrinites  are  frequently  seen. 
Wengen  Beds  (part).  Ashy  beds,  exposed  in  the  streams  below  Lacedel. 
Debris  at  lower  levels. 
Middle  St.  Cassian 
(see  ‘  Romerlo  ’  in  , 
the  List  of  Fos- " 
sils). 
Lower  St.  Cassian.  1 
The  character  of  the  fossils  which  occur  in  the  five  lowermost 
divisions  of  the  above  section ;  the  great  predominance  in  number  of 
the  small  bivalves,  gasteropods,  cidarid  spines,  corals,  and  sponges ; 
as  well  as  the  lithological  character  of  the  hard  limestone,  the 
marly  beds  and  loose  ferruginous  earth  in  which  the  fauna  occurs, 
enable  one  to  refer  these  horizons  with  certainty  to  the  St.  Cassian 
Series. 
The  Middle  St.  Cassian  strata  are  present  on  the  hill  and  the 
4  Wiese’  west  of  Eomerlo,  on  the  slopes  west  of  the  Yerviers  chalets, 
again  south  of  the  Costeana  stream,  and  west  of  Ospizio  in  Falzarego. 
The  Upper  St.  Cassian  strata  have  their  chief  exposure  south-east 
from  Yerviers  and  in  the  stream-sources  below  the  Majorera  ridge, 
conformably  above  the  wide  outcrop  of  Middle  St.  Cassian  on  the 
‘  Wiese/  The  fossils  found  in  the  last-named  strata  are  at  once 
recognizable  as  essentially  a  ‘Stuores’  fauna,  but  in  the  Upper 
St.  Cassian,  although  many  species  of  corals,  gasteropods,  etc.,  are 
characteristic  of  the  4  Stuores  ’  horizon,  a  certain  number  of  species 
are  common  to  both  St.  Cassian  and  Eaibl  faunas  (e.g.  Gvunwaldia 
( Cassianella )  decussata ,  Myophoriopis  linecita ,  Avicula  Gea,  Ptycho- 
stoma  pleurotomoides ,  Cidaris  dorsata ),  while  several  species,  such 
as  the  very  commonly  occurring  Avicula ,  n.  sp.,  and  Placunopsis, 
n.  sp.,  have  not  yet  been  found  in  any  other  locality. 
The  palaeontological  relations  of  these  two  horizons  of  St.  Cassian 
strata  are  more  fully  discussed  in  Part  YII.  of  this  paper  (p.  45). 
As  has  already  been  said,  the  4  Heiligkreuz  strata  ’  of  the  previous 
section  contain  a  limited  fauna  which  seems  to  diverge  from  that 
of  the  Middle  St.  Cassian  strata  of  Stuores.  The  fossils  of  the 
4  Heiligkreuz  strata  ’do  not  definitely  prove  a  higher  horizon ;  they 
might  be  simply  a  local  facies.  It  is  therefore  very  important  to 
find  that  two  of  the  characteristic  species  found  in  the  4  Heiligkreuz 
strata,’  Ptychostoma  pleurotomoides  and  Naticopsis  neritacea ,  are 
common  in  these  Upper  St.  Cassian  strata  of  the  Cortina  district. 
This  fact  suggests  that  the  4  Heiligkreuz  strata  ’  are  the  equivalent 
in  part  of  the  Upper  St.  Cassian  horizon. 
I  have  dwelt  -at  some  length  on  the  St.  Cassian  strata  of  Cortina, 
chiefly  because  they  have  for  the  most  part  been  included  with 
the  Wengen  strata  by  Mojsisovics,  with  the  Schlern-plateau  strata 
(Eaibl  fauna)  by  Loretz,  and  also  because  the  fauna  up  to  this  time 
was  comparatively  little  known. 
