﻿l62 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  are 
  of 
  specimens 
  so 
  broken 
  as 
  to 
  expose 
  the 
  interior. 
  Solid 
  flint 
  

   has 
  replaced 
  the 
  outer 
  part 
  of 
  the 
  sponge 
  body, 
  but 
  in 
  the 
  dis- 
  

   integrated 
  silica 
  of 
  the 
  interior 
  the 
  tube 
  of 
  the 
  cloaca 
  stands 
  verti- 
  

   cal 
  with 
  hardened 
  walls 
  about 
  which 
  the 
  worm 
  tube 
  seems 
  to 
  coil 
  

   like 
  a 
  beanstalk 
  on 
  a 
  pole. 
  The 
  transparent 
  section 
  which 
  is 
  re- 
  

   produced 
  from 
  a 
  direct 
  print, 
  shows 
  with 
  probably 
  more 
  accuracy 
  

   the 
  actual 
  distance 
  of 
  the 
  tube 
  from 
  the 
  cloaca. 
  It 
  is 
  extremely 
  

   instructive 
  to 
  note 
  that 
  the 
  direction 
  of 
  coiling 
  is 
  unlike 
  in 
  the 
  

   two 
  specimens 
  exposing 
  the 
  spiral, 
  while 
  in 
  the 
  section 
  it 
  would 
  be 
  

   impossible 
  to 
  determine 
  whether 
  the 
  course 
  of 
  the 
  coiling 
  is 
  dex- 
  

   tral 
  or 
  sinistral. 
  

  

  Barnacles 
  and 
  Corals 
  

  

  The 
  barnacles 
  of 
  today 
  express 
  to 
  us 
  one 
  of 
  the 
  extreme 
  reswrfts 
  

   of 
  modification 
  through 
  adaptation 
  to 
  a 
  parasitic 
  condition. 
  I 
  

   have 
  ventured 
  to 
  suggest 
  on 
  a 
  previous 
  occasion 
  that 
  the 
  Siluric 
  

   barnacles 
  of 
  the 
  genus 
  Lepidocoleus 
  [pi. 
  5, 
  fig. 
  3] 
  are 
  an 
  expression 
  

   of 
  these 
  creatures 
  before 
  such 
  modifications 
  set 
  in. 
  It 
  is 
  regularly 
  

   segmented 
  throughout 
  its 
  length, 
  its 
  biserial 
  row 
  of 
  plates 
  'being 
  

   open 
  on 
  one 
  side 
  only 
  for 
  the 
  protrusion 
  of 
  the 
  appendages. 
  The 
  

   forms 
  known 
  as 
  Turrilepas, 
  Plumulites 
  and 
  Strobilepis 
  of 
  the 
  

   Devonic, 
  are 
  not 
  of 
  greatly 
  different 
  structure. 
  We 
  know" 
  however 
  

   of 
  fully 
  modified 
  acorn 
  barnacles 
  in 
  the 
  Devonic 
  Protobalanus 
  and 
  

   Palaeocreusia. 
  The 
  latter 
  is 
  parasitic 
  on 
  a 
  Favosite 
  coral 
  of 
  the 
  

   Onondaga 
  limestone 
  (Lower 
  Devonic), 
  in 
  which 
  it 
  appears 
  to 
  be 
  

   embedded 
  by 
  the 
  overgrowth 
  of 
  the 
  polypites 
  rather 
  than 
  by 
  

   burrowing 
  its 
  way 
  into 
  the 
  colony 
  as 
  do 
  sometimes 
  the, 
  acorn 
  

   barnacles 
  of 
  the 
  present 
  [pi. 
  5, 
  fig. 
  4, 
  5]. 
  

  

  Crinoids 
  and 
  Cystids 
  with 
  Gastropods 
  

  

  We 
  are 
  here 
  presented 
  with 
  what 
  appear 
  to 
  be 
  instances 
  of 
  

   genuinely 
  dependent 
  parasitism 
  — 
  w 
  T 
  here 
  an 
  attached 
  organism 
  

   relies 
  upon 
  its 
  host 
  for 
  its 
  nutriment 
  and 
  existence. 
  They 
  con- 
  

   stitute 
  the 
  earliest 
  instances 
  we 
  can 
  cite 
  of 
  a 
  dependence 
  between 
  

   organisms 
  that 
  has 
  become 
  essential 
  rather 
  than 
  merely 
  convenient 
  

   and 
  it 
  is 
  of 
  extraordinary 
  interest 
  because 
  we 
  find 
  some 
  clue 
  here 
  

   to 
  the 
  origin 
  of 
  the 
  habit. 
  The 
  attachment 
  of 
  the 
  limpetlike 
  

   gastropod 
  Platyceras 
  to 
  the 
  calyx 
  of 
  the 
  crinoid 
  of 
  the 
  Paleozoic 
  has 
  

   already 
  been 
  referred 
  to 
  and 
  many 
  instances 
  of 
  it 
  have 
  been 
  cited 
  

  

  