﻿102 
  Hatcher 
  — 
  Sedimentary 
  Rocks 
  of 
  Southern 
  Patagonia. 
  

  

  already 
  found 
  to 
  exist 
  among 
  species 
  given 
  by 
  Dr. 
  Ameghino 
  

   as 
  characteristic 
  of 
  the 
  different 
  beds, 
  which 
  that 
  author 
  has 
  

   considered 
  as 
  distinct. 
  

  

  Among 
  the 
  collections 
  from 
  San 
  Julian, 
  the 
  type 
  locality 
  

   for 
  the 
  Piso 
  Juliense, 
  he 
  finds 
  at 
  Oven 
  Point 
  all 
  the 
  Juliense 
  

   species 
  but 
  two 
  {Pecten 
  prwnuncius 
  and 
  Hypechinus 
  pata- 
  

   gonicus) 
  mingled 
  with 
  Ostrea 
  ingens, 
  a 
  Leonense 
  and 
  Supra- 
  

   patagonica 
  species, 
  while 
  at 
  Darwin 
  Station, 
  a 
  higher 
  horizon, 
  

   these 
  Juliense 
  species 
  are 
  found 
  : 
  Terebratella 
  patagonica, 
  

   Pecten 
  geminatus, 
  Siphonalia 
  noachina. 
  

  

  At 
  the 
  mouth 
  of 
  the 
  Santa 
  Cruz 
  River, 
  there 
  are 
  found 
  

   mingled 
  together 
  in 
  the 
  same 
  horizon 
  all 
  the 
  species 
  given 
  by 
  

   Ameghino 
  as 
  characteristic 
  of 
  his 
  Piso 
  Leonense, 
  together 
  with 
  

   the 
  following 
  Juliense 
  species 
  : 
  Terebratella 
  patagonica, 
  Pecten 
  

   geminatus, 
  Schizaster 
  ameghinoi 
  and 
  these 
  Supra-Patagonian 
  

   forms 
  : 
  Ostrea 
  ingens, 
  Amathusia 
  angulata, 
  Dentalium 
  octo- 
  

   costatum. 
  

  

  From 
  the 
  Mt. 
  of 
  Observation 
  we 
  have 
  in 
  the 
  lowermost 
  

   horizon 
  Cucullcea 
  alta, 
  a 
  Leonense 
  species, 
  while 
  in 
  the 
  upper 
  

   horizon 
  or 
  Supra-Patagonian 
  beds, 
  there 
  are 
  Terebratella 
  pata- 
  

   gonica 
  and 
  Siphonalia 
  noachina, 
  Juliense 
  species, 
  mingled 
  with 
  

   Ostrea 
  ingens, 
  a 
  Leonense 
  and 
  Supra-Patagonian 
  species, 
  and 
  

   Voluta 
  ameghinoi 
  and 
  Dentalium, 
  octocostatum, 
  Supra-Pata- 
  

   gonian 
  species. 
  

  

  At 
  the 
  base 
  of 
  the 
  marine 
  Tertiary 
  in 
  the 
  Lake 
  Pueyrredon 
  

   section, 
  which 
  according 
  to 
  Ameghino 
  should 
  be 
  Supra-Pata- 
  

   gonian 
  beds, 
  we 
  have 
  the 
  following 
  five 
  Juliense 
  species, 
  Tere- 
  

   bratella 
  patagonica, 
  Bouchardia 
  Zittelli, 
  Rhynchonella 
  nigri- 
  

   cans, 
  Pecten 
  geminatus, 
  Echinarachinus 
  juliense 
  and 
  Perna 
  

   quadrisulcata, 
  a 
  Leonense 
  species, 
  together 
  with 
  Ostrea 
  ingens, 
  

   a 
  Leonense 
  and 
  Supra-Patagonian 
  species. 
  

  

  In 
  the 
  uppermost 
  of 
  the 
  Supra-Patagonian 
  beds 
  on 
  the 
  

   upper 
  Rio 
  Chalia 
  and 
  at 
  Shell 
  Gap 
  or 
  Rio 
  Chico, 
  the 
  follow- 
  

   ing 
  three 
  Juliense 
  species, 
  Terebratella 
  patagonica, 
  Rhyn- 
  

   chonella 
  nigricans, 
  Mchinarachinus 
  juliensis, 
  occur 
  associated 
  

   with 
  Turritella 
  argentina, 
  a 
  Leonense 
  species, 
  and 
  Ostrea 
  

   ingens, 
  from 
  the 
  Leonense 
  and 
  Supra-Patagonian 
  beds. 
  

  

  In 
  one 
  small 
  block 
  six 
  inches 
  in 
  diameter, 
  from 
  the 
  mouth 
  

   of 
  the 
  Santa 
  Cruz 
  River. 
  Terebratella 
  patagonica, 
  and 
  Pecten 
  

   geminatus, 
  Juliense 
  species, 
  were 
  found 
  associated 
  with 
  Stru- 
  

   thiolaria 
  ornata, 
  which 
  according 
  to 
  Ameghino 
  is 
  character- 
  

   istic 
  of 
  the 
  Piso 
  Leonense. 
  

  

  In 
  the 
  above 
  lists 
  it 
  will 
  be 
  noticed 
  that 
  only 
  the 
  character- 
  

   istic 
  species 
  as 
  given 
  by 
  Ameghino 
  are 
  included 
  and 
  it 
  is 
  seen 
  

   that 
  in 
  every 
  instance 
  there 
  has 
  been 
  found 
  a 
  mingling 
  in 
  the 
  

   same 
  horizon 
  of 
  these 
  supposedly 
  characteristic 
  forms. 
  While 
  

   in 
  some 
  instances, 
  as 
  at 
  Lake 
  Pueyrredon, 
  upper 
  Rio 
  Chalia 
  

  

  