﻿124 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  b6 
  

  

  Atlantic 
  Ocean, 
  because 
  this 
  would 
  require 
  a 
  study 
  of 
  the 
  specimens 
  

   on 
  which 
  such 
  reports 
  were 
  based, 
  and 
  these 
  specimens 
  are 
  not 
  now 
  

   available. 
  

  

  The 
  genus 
  Ophioscion 
  is 
  closely 
  related 
  to 
  Bairdiella 
  Gill 
  and 
  

   Stellifer 
  Oken. 
  Meek 
  and 
  Hildebrand 
  (Marine 
  fishes 
  of 
  Panama, 
  

   vol. 
  2, 
  p. 
  611, 
  1925) 
  separated 
  Stellifer 
  from 
  Bairdiella 
  and 
  O'phioscion 
  

   in 
  their 
  key 
  on 
  the 
  basis 
  of 
  the 
  skull 
  being 
  "excessively 
  cavernous, 
  

   spongy 
  to 
  the 
  touch." 
  I 
  had 
  some 
  difficulty 
  separating 
  the 
  various 
  

   species 
  referred 
  to 
  these 
  genera 
  by 
  this 
  character, 
  and 
  so 
  1 
  made 
  a 
  

   dissection 
  of 
  the 
  upper 
  surfaces 
  of 
  the 
  skull, 
  removing 
  the 
  scales 
  and 
  

   skin, 
  thus 
  exposing 
  the 
  nature 
  of 
  the 
  cavernous 
  skull. 
  Bairdiella 
  

   chrysura 
  (Lacepede), 
  Ophioscion 
  typicus 
  Gill, 
  and 
  Stellifer 
  rastrifer 
  

   (Jordan) 
  all 
  have 
  cavernous 
  skulls 
  dorsally, 
  and 
  also 
  around 
  the 
  orbits 
  

   occur 
  narrow 
  bony 
  bridges 
  or 
  stays 
  supporting 
  the 
  overlying 
  skin 
  

   and 
  scales. 
  Stellifer 
  has 
  a 
  broader 
  interorbital 
  space, 
  and 
  thus 
  the 
  

   caverns 
  are 
  a 
  little 
  broader 
  and 
  by 
  touch 
  can 
  be 
  felt 
  a 
  trifle 
  more 
  easily 
  

   than 
  the 
  slightly 
  narrower 
  caverns 
  in 
  the 
  other 
  two 
  genera. 
  My 
  dis- 
  

   sections 
  indicate 
  that 
  the 
  caverns 
  are 
  weJl 
  developed 
  in 
  all 
  three 
  gen- 
  

   era 
  ^ 
  and 
  are 
  of 
  little 
  value 
  as 
  a 
  diagnostic 
  character 
  in 
  the 
  separation 
  

   of 
  these 
  three 
  genera, 
  especially 
  if 
  the 
  specimens 
  are 
  weU 
  hardened 
  

   in 
  preservation. 
  

  

  Ophioscion 
  is 
  said 
  to 
  differ 
  from 
  Bairdiella 
  by 
  having 
  the 
  lower 
  

   spine 
  of 
  the 
  preopercle 
  pointing 
  straight 
  backward 
  and 
  a 
  little 
  down- 
  

   ward, 
  whereas 
  in 
  Bairdiella 
  it 
  is 
  said 
  to 
  be 
  hooked 
  downward. 
  The 
  

   lower 
  preopercular 
  spine 
  in 
  these 
  genera 
  is 
  so 
  variable 
  among 
  the 
  

   various 
  species 
  of 
  Bairdiella 
  and 
  Ophioscion 
  that 
  I 
  cast 
  serious 
  doubt 
  

   on 
  its 
  usefulness 
  as 
  a 
  character. 
  None 
  of 
  the 
  species 
  of 
  Ophioscion 
  has 
  

   any 
  of 
  the 
  preopercular 
  spines 
  hooked 
  downward. 
  However, 
  some 
  

   individuals, 
  especially 
  young 
  examples 
  of 
  Bairdiella 
  chrysura^ 
  like- 
  

   wise 
  do 
  not 
  have 
  the 
  lower 
  preopercular 
  spine 
  hooked 
  downward, 
  

   although 
  in 
  adults 
  of 
  Bairdiella 
  that 
  spine 
  is 
  hooked 
  downward. 
  

  

  I 
  have 
  searched 
  for 
  characters 
  to 
  separate 
  these 
  three 
  genera 
  but 
  

   have 
  found 
  indications 
  of 
  overlapping, 
  and 
  so 
  the 
  following 
  char- 
  

   acters 
  are 
  not 
  wholly 
  satisfactory, 
  although 
  the 
  genera 
  can 
  be 
  sepa- 
  

   rated 
  by 
  them 
  when 
  taken 
  together 
  : 
  

  

  Bairdiell'G, 
  with 
  an 
  obliquely 
  terminal 
  mouth; 
  both 
  jaws 
  of 
  nearly 
  

   same 
  length; 
  lower 
  jaw 
  with 
  minute 
  teeth 
  in 
  a 
  narrow 
  band 
  of 
  two 
  or 
  

   three 
  rows 
  forward 
  and 
  in 
  a 
  single 
  row 
  of 
  slightly 
  enlarged 
  teeth 
  

   posteriorly 
  ; 
  the 
  pair 
  of 
  small 
  pores 
  at 
  tip 
  of 
  chin 
  close 
  together 
  and 
  

   lying 
  more 
  or 
  less 
  in 
  a 
  shallow 
  depression 
  (fig. 
  5, 
  &) 
  and 
  the 
  margin 
  of 
  

   the 
  snout 
  lacking 
  the 
  small 
  lobes 
  at 
  each 
  side 
  of 
  the 
  median 
  pore 
  

  

  * 
  I 
  removed 
  the 
  skin 
  and 
  scales 
  from 
  specimens 
  representing 
  various 
  species 
  usually 
  

   referred 
  to 
  the 
  following 
  genera 
  and 
  found 
  the 
  dorsal 
  part 
  of 
  the 
  skull 
  to 
  be 
  cavernous 
  : 
  

   TJmhrina 
  Cuvier 
  ; 
  ilicropogon 
  Cuvier 
  and 
  Valenciennes 
  ; 
  Plagioscton 
  Gill 
  ; 
  Macrodon 
  Schinz 
  ; 
  

   Gynoscion 
  Gill 
  ; 
  Corvula 
  Jordan 
  and 
  Bigenmann 
  ; 
  Larimus 
  Cuvier 
  and 
  Valenciennes. 
  In 
  

   Mentlcirrhus 
  Gill 
  the 
  caverns 
  were 
  much 
  smaller 
  than 
  in 
  the 
  other 
  genera 
  examined. 
  

  

  