﻿376 
  A. 
  M. 
  Edwards 
  — 
  Infusorial 
  Earths 
  of 
  Pacific 
  Coast. 
  

  

  the 
  sea-bottom 
  or 
  shell 
  cleanings, 
  as 
  well 
  as 
  harbor 
  muds, 
  

   the 
  contents 
  of 
  the 
  intestines 
  of 
  marine 
  and 
  fresh 
  water 
  ani- 
  

   mals 
  and 
  the 
  like 
  be 
  indicated. 
  However, 
  I 
  think 
  that 
  nearly 
  

   all 
  gatherings 
  may 
  be 
  fairly 
  grouped 
  under 
  the 
  four 
  heads 
  I 
  

   have 
  adopted. 
  

  

  As 
  the 
  tendency 
  of 
  most 
  persons 
  who 
  have 
  turned 
  their 
  

   attention 
  to 
  the 
  Diatomacese, 
  which 
  are 
  the 
  organisms 
  I 
  shall 
  

   more 
  particularly 
  consider 
  in 
  this 
  report, 
  has 
  been 
  towards 
  

   looking 
  for 
  differences 
  where 
  similitudes 
  should 
  have 
  been 
  

   searched 
  after, 
  I 
  must 
  be 
  permitted 
  to 
  say 
  a 
  few 
  words 
  on 
  that 
  

   point. 
  The 
  progress 
  of 
  time, 
  the 
  more 
  especially 
  if 
  it 
  be 
  very 
  

   much 
  extended, 
  may, 
  and 
  in 
  fact 
  will, 
  so 
  change 
  the 
  apparent 
  

   characters 
  of 
  all 
  living 
  organisms 
  that 
  they 
  can 
  hardly, 
  in 
  the 
  

   present 
  condition 
  of 
  our 
  knowledge, 
  be 
  distinguished 
  one 
  from 
  

   another 
  ; 
  but 
  they 
  will 
  most 
  assuredly 
  revert 
  to 
  the 
  parent 
  

   type, 
  even 
  if 
  the 
  modifying 
  influence 
  be 
  continued 
  in 
  power, 
  

   so 
  strong, 
  so 
  persistent, 
  so 
  fundamental 
  is 
  the 
  inherent 
  germ- 
  

   force 
  implanted 
  in 
  the 
  individual. 
  The 
  Diatomacese 
  are 
  not 
  

   so 
  liable 
  to 
  be 
  influenced 
  by 
  outward 
  circumstances, 
  apparently, 
  

   as 
  some 
  other 
  groups 
  ; 
  but, 
  at 
  the 
  same 
  time, 
  understood 
  energies 
  

   do 
  affect 
  them 
  very 
  materially, 
  so 
  as 
  to 
  change 
  their 
  outline, 
  

   for 
  instance, 
  leaving 
  their 
  main 
  characters 
  of 
  sculpture 
  intact. 
  

   I 
  very 
  much 
  doubt 
  if 
  time 
  has 
  as 
  great 
  or 
  as 
  lasting 
  an 
  effect 
  

   in 
  causing 
  such 
  modifications 
  as 
  locality 
  and, 
  therefore, 
  must 
  

   consider 
  the 
  use 
  of 
  this 
  point 
  as 
  a 
  basis 
  for 
  distinguishing 
  

   species 
  to 
  be 
  unscientific 
  and 
  unjustified, 
  at 
  least 
  with 
  regard 
  

   to 
  these 
  organisms. 
  

  

  Among 
  the 
  specimens 
  I 
  have 
  to 
  report 
  upon 
  herein, 
  we 
  

   have 
  examples 
  of 
  all 
  of 
  the 
  four 
  groups 
  I 
  have 
  adopted, 
  as 
  

   Recent, 
  Lacustrine, 
  Sedimentary, 
  and 
  sub-Plutonic, 
  under 
  which 
  

   head 
  are 
  to 
  be 
  placed 
  the 
  tripolis 
  of 
  commerce 
  and 
  Marine 
  

   Fossil 
  strata. 
  

  

  The 
  first 
  Lacustrine 
  Sedimentary 
  deposit 
  discovered 
  in 
  this 
  

   country 
  was 
  that 
  found 
  by 
  the 
  late 
  Prof. 
  J. 
  W. 
  Bailey 
  at 
  

   West 
  Point, 
  ]ST. 
  Y., 
  and 
  was 
  described 
  by 
  him 
  in 
  volume 
  

   xxxv 
  of 
  this 
  Journal. 
  Since 
  that 
  time 
  similar 
  deposits 
  

   have 
  been 
  discovered 
  at 
  many 
  widely 
  separated 
  points 
  in 
  this 
  

   country 
  and 
  in 
  Europe, 
  which 
  bears 
  out 
  the 
  opinion 
  expressed 
  

   by 
  Prof. 
  Bailey 
  that 
  strata 
  resembling 
  the 
  West 
  Point 
  earth 
  

   in 
  general 
  characters 
  would 
  be 
  found 
  under 
  every 
  bog 
  in 
  the 
  

   country. 
  In 
  Europe 
  such 
  has 
  been 
  the 
  case, 
  as 
  the 
  Lough 
  

   Mourne, 
  Premnay, 
  Peterhead, 
  Toome 
  Bridge 
  and 
  Mull 
  in 
  

   Great 
  Britain 
  and 
  others 
  on 
  the 
  Continent 
  bear 
  testimony. 
  

  

  After 
  receiving 
  from 
  Mr. 
  Gibbs 
  the 
  collection 
  of 
  specimens 
  

   I 
  have 
  already 
  given 
  a 
  list 
  of, 
  he 
  also 
  sent 
  three 
  more, 
  and 
  

   these 
  I 
  shall 
  include 
  here, 
  as 
  they 
  come 
  from 
  the 
  same 
  portion 
  

   of 
  country 
  as 
  the 
  first. 
  They 
  are 
  marked 
  as 
  below 
  : 
  

  

  