﻿EUGNATHID^E. 
  

  

  289 
  

  

  plates. 
  There 
  are 
  two 
  very 
  large 
  suborbitals 
  (or 
  postorbitals) 
  

   immediately 
  in 
  front 
  of 
  the 
  preoperculum, 
  and 
  there 
  is 
  a 
  circum- 
  

   orbital 
  ring 
  of 
  small 
  plates 
  of 
  irregular 
  size. 
  At 
  least 
  one 
  large 
  

   preorbital 
  plate 
  may 
  also 
  be 
  noticed. 
  The 
  maxilla 
  is 
  comparatively 
  

   robust, 
  long 
  and 
  narrow, 
  somewhat 
  deepened 
  behind 
  and 
  with 
  a 
  

   stout 
  inwardly 
  directed 
  process 
  near 
  its 
  anterior 
  extremity. 
  Its 
  

   hinder 
  margin 
  is 
  excavated 
  by 
  a 
  sharp 
  re-entering 
  angle, 
  and 
  the 
  

   oral 
  margin 
  is 
  straight 
  or 
  slightly 
  concave. 
  Above 
  the 
  posterior 
  

   half 
  of 
  the 
  bone 
  is 
  a 
  long 
  narrow 
  supramaxilla, 
  which 
  is 
  pointed 
  in 
  

   front 
  but 
  truncated 
  behind. 
  The 
  premaxilla 
  is 
  antero-posteriorly 
  

   extended, 
  not 
  deepened, 
  but 
  with 
  a 
  short 
  narrow 
  process 
  rising 
  

   upwards 
  near 
  the 
  middle 
  of 
  its 
  superior 
  border. 
  The 
  hyomandi- 
  

   bular 
  is 
  elongated, 
  much 
  laterally 
  compressed, 
  and 
  with 
  a 
  large 
  

   process 
  for 
  the 
  support 
  of 
  the 
  operculum. 
  Its 
  long 
  axis 
  is 
  only 
  

   slightly 
  arcuated, 
  and 
  its 
  expanded 
  lower 
  extremity 
  meets 
  both 
  the 
  

   quadrate 
  and 
  the 
  symplectic. 
  The 
  ]atter 
  is 
  an 
  elongated 
  triangular 
  

   bone, 
  its 
  narrow 
  base 
  turned 
  upwards 
  in 
  contact 
  with 
  the 
  hyoman- 
  

   dibular, 
  its 
  thickened 
  apex 
  apparently 
  extending 
  to 
  the 
  articular 
  

   condyle 
  of 
  the 
  quadrate. 
  The 
  entopterygoid 
  is 
  a 
  large 
  laminar 
  bone 
  

   covered 
  on 
  the 
  oral 
  face 
  by 
  minute 
  granulations 
  resembling 
  those 
  

   of 
  the 
  parasphenoid. 
  The 
  ectopterygoid 
  and 
  palatine 
  are 
  not 
  

   certainly 
  known. 
  -The 
  mandible 
  is 
  much 
  deepened 
  in 
  the 
  coronoid 
  

   region, 
  but 
  the 
  limits 
  of 
  the 
  coronoid 
  bone 
  are 
  rarely 
  observed 
  ; 
  it 
  

   is 
  shown 
  in 
  the 
  original 
  of 
  fig. 
  34, 
  p. 
  293. 
  The 
  angular 
  element 
  

   is 
  of 
  moderate 
  size, 
  meeting 
  the 
  dentary 
  in 
  a 
  wavy 
  suture 
  in 
  the 
  

   coronoid 
  region. 
  The 
  dentary 
  itself 
  also 
  rises 
  in 
  the 
  front 
  part 
  of 
  

   this 
  elevation, 
  but 
  rapidly 
  tapers 
  and 
  becomes 
  very 
  narrow 
  at 
  the 
  

   symphysis 
  ; 
  it 
  bears 
  a 
  single 
  series 
  of 
  large 
  conical 
  teeth. 
  The 
  

   splenial, 
  also 
  partly 
  extended 
  into 
  the 
  coronoid 
  elevation, 
  is 
  a 
  thin 
  

   laminar 
  bone 
  behind, 
  but 
  much 
  thickened 
  in 
  front, 
  where 
  it 
  enters 
  

   and 
  strengthens 
  the 
  mandibular 
  symphysis. 
  Its 
  teeth 
  are 
  all 
  

   minute, 
  those 
  in 
  its 
  hinder 
  portion 
  being 
  mere 
  granulations. 
  The 
  

   ceratohyal 
  is 
  very 
  large, 
  deep 
  and 
  laterally 
  compressed 
  behind, 
  but 
  

   apparently 
  depressed 
  in 
  front 
  so 
  that 
  its 
  inferior 
  border 
  exhibits 
  a 
  

   narrow 
  flattened 
  horizontal 
  expansion. 
  The 
  triangular 
  epihyal 
  is 
  

   small 
  and 
  thin 
  ; 
  the 
  hypohyal 
  on 
  each 
  side 
  is 
  a 
  still 
  smaller, 
  but 
  

   square 
  and 
  much 
  thicker 
  bone. 
  

  

  The 
  branchial 
  arches 
  are 
  delicate 
  and 
  exhibit 
  the 
  channel 
  

   specially 
  characteristic 
  of 
  modern 
  bony 
  fishes. 
  They 
  bear 
  a 
  much- 
  

   spaced 
  series 
  of 
  large 
  slender 
  gill-rakers, 
  which 
  are 
  straight 
  and 
  

   acutely 
  pointed. 
  The 
  basibranchials 
  are 
  slender. 
  The 
  opercular 
  

   apparatus 
  is 
  complete 
  : 
  the 
  branchiostegal 
  rays 
  are 
  laminar 
  ; 
  and 
  

  

  PART 
  III. 
  T7 
  

  

  