﻿36 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  interest. 
  The 
  investigation 
  has 
  progressed 
  sufficiently 
  to 
  permit 
  the 
  

   restoration 
  of 
  all 
  the 
  hard 
  anatomy 
  of 
  the 
  principal 
  genera 
  of 
  the 
  

   order. 
  Stylonurus, 
  which 
  has 
  been 
  known 
  as 
  one 
  of 
  the 
  largest 
  

   of 
  these 
  creatures, 
  attaining 
  a 
  length 
  of 
  5 
  — 
  6 
  feet, 
  proves, 
  on 
  study 
  

   of 
  smaller 
  species 
  from 
  Otisville, 
  materially 
  different 
  in 
  structure 
  

   from 
  the 
  generally 
  accepted 
  restoration. 
  It 
  has 
  also 
  been 
  possible 
  

   to 
  restore 
  the 
  genera 
  Eusarcus 
  and 
  Dolichopterus 
  with 
  all 
  their 
  

   appendages 
  and 
  to 
  assemble 
  all 
  parts 
  of 
  the 
  integument 
  of 
  the 
  

   largest 
  Pter}'^otus 
  occurring 
  in 
  the 
  New 
  York 
  formations. 
  Other 
  

   results 
  of 
  significance 
  are 
  the 
  recognition 
  of 
  the 
  genus 
  Drepanop- 
  

   terus; 
  the 
  identity 
  of 
  the 
  eye 
  structure 
  of 
  Pterygotus 
  with 
  that 
  

   of 
  Limulus 
  shown 
  by 
  the 
  presence 
  of 
  an 
  outer 
  smooth 
  thick 
  

   cornea 
  which 
  is 
  separable 
  from 
  an 
  inner 
  layer 
  of 
  lenses 
  ; 
  the 
  

   demonstration 
  that 
  the 
  chelicerae 
  of 
  Pterygotus 
  consist 
  of 
  long 
  

   un 
  jointed 
  arms 
  carrying 
  the 
  terminal 
  pincers 
  ; 
  and 
  the 
  close 
  relation- 
  

   ship 
  of 
  the 
  genera 
  Stylonurus 
  and 
  Dolichopterus 
  brought 
  out 
  by 
  

   transitional 
  forms 
  and 
  the 
  identity 
  of 
  new 
  structures 
  observed 
  in 
  

   their 
  New 
  York 
  representatives. 
  

  

  The 
  genus 
  Stylonurus 
  is 
  resolved 
  into 
  three 
  subdivisions 
  for 
  

   which 
  the 
  subgeneric 
  terms 
  Stylonurus 
  sensu 
  stricto, 
  Ctenopterus 
  

   and 
  Homalopterus 
  are 
  introduced. 
  These 
  divisions 
  are 
  based 
  

   mainly 
  on 
  the 
  character 
  of 
  the 
  legs. 
  

  

  The 
  genus 
  Hughmilleria 
  has 
  been 
  shown 
  to 
  agree 
  in 
  the 
  struc- 
  

   ture 
  of 
  its 
  compound 
  eyes 
  with 
  Eurypterus, 
  although 
  the 
  position 
  

   of 
  these 
  suggests 
  a 
  closer 
  relationship 
  to 
  Pterygotus. 
  

  

  The 
  Cambric 
  genus 
  Strabops 
  possesses 
  the 
  full 
  complement 
  of 
  

   12 
  dorsal 
  segments 
  instead 
  of 
  11, 
  as 
  hitherto 
  supposed, 
  and 
  has 
  

   small 
  compound 
  eyes 
  placed 
  far 
  back 
  and 
  near 
  the 
  lateral 
  margin. 
  

   The 
  investigation 
  of 
  the 
  larval 
  forms 
  of 
  a 
  number 
  of 
  Siluric 
  species 
  

   has 
  shown 
  that 
  some 
  of 
  these 
  pass 
  through 
  a 
  stage 
  identical 
  in 
  its 
  

   most 
  important 
  features 
  with 
  the 
  adult 
  Cambric 
  Strabops. 
  

  

  The 
  ontogeny 
  of 
  Eurypterids 
  is 
  for 
  the 
  first 
  time 
  investigated 
  and 
  

   the 
  development 
  of 
  species 
  of 
  the 
  genera 
  Eurypterus, 
  Eusarcus, 
  

   Hughmilleria, 
  Pterygotus 
  and 
  Stylonurus 
  is 
  traced 
  as 
  far 
  back 
  as 
  

   the 
  nepionic 
  or 
  larval 
  stage, 
  and 
  a 
  number 
  of 
  larval 
  characters 
  

   are 
  established 
  which 
  appear 
  to 
  be 
  common 
  to 
  all 
  and 
  of 
  signifi- 
  

   cance 
  in 
  phylogenetic 
  relation. 
  

  

  Both 
  the 
  restorations 
  of 
  the 
  genera 
  and 
  the 
  investigation 
  of 
  the 
  

   ontogeny 
  have 
  allowed 
  conclusions 
  on 
  the 
  phylogeny 
  of 
  the 
  

   Eurypterids, 
  as 
  well 
  as 
  their 
  morphology 
  and 
  mode 
  of 
  life. 
  

  

  