﻿520 
  

  

  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  [32] 
  

  

  observed 
  by 
  the 
  writer 
  came 
  from 
  Northville, 
  Mich., 
  and 
  were 
  hatched 
  

   on 
  the 
  15th 
  of 
  June, 
  1885, 
  at 
  the 
  Central 
  Station, 
  Washington. 
  

  

  XIV. 
  — 
  SCOMBEROMORUS 
  MACULATUS 
  (MlTCH.) 
  

  

  Mackerel.) 
  

  

  J. 
  & 
  G. 
  (Spanish 
  

  

  Figs. 
  46 
  to 
  56, 
  plate 
  x, 
  relate 
  to 
  this 
  species 
  and 
  give 
  a 
  few 
  details 
  

   of 
  structure 
  which 
  it 
  was 
  not 
  possible 
  to 
  work 
  out 
  by 
  the 
  methods 
  of 
  

   study 
  which 
  I 
  was 
  obliged 
  to 
  pursue 
  at 
  the 
  time 
  my 
  first 
  paper 
  was 
  

   written. 
  

  

  Fig. 
  46 
  represents 
  a 
  transverse 
  section 
  through 
  the 
  hist 
  cerebral 
  

   vesicle; 
  the 
  nasal 
  pit 
  is 
  also 
  cut 
  through 
  at 
  na. 
  Fig. 
  47 
  represents 
  a 
  

   section 
  through 
  the 
  mid-brain 
  and 
  the 
  origin 
  of 
  the 
  optic 
  nerves. 
  A 
  

   segmental 
  sense 
  organ 
  is 
  also 
  cut 
  through 
  just 
  above 
  the 
  front 
  portion 
  

   of 
  the 
  eye. 
  Fig. 
  48 
  is 
  from 
  a 
  section 
  a 
  little 
  farther 
  back 
  than 
  the 
  pre- 
  

   ceding. 
  Fig. 
  49 
  is 
  a 
  very 
  much 
  enlarged 
  representation 
  of 
  a 
  section 
  

   through 
  one 
  of 
  the 
  segmental 
  sense 
  organs, 
  showing 
  the 
  columnar 
  

   character 
  of 
  the 
  cells 
  of 
  the 
  lower 
  layer 
  of 
  the 
  integument 
  in 
  these 
  struct- 
  

   ures. 
  Fig. 
  50 
  is 
  a 
  representation 
  of 
  a 
  section 
  cutting 
  transversely 
  

   through 
  the 
  hinder 
  region 
  of 
  the 
  mid-brain 
  and 
  shows 
  the 
  course 
  of 
  the 
  

   fibers 
  of 
  the 
  optic 
  nerves 
  through 
  the 
  retinal 
  walls. 
  Fig. 
  51 
  represents 
  

   a 
  cross-section 
  through 
  the 
  fore 
  part 
  of 
  the 
  medulla 
  oblongata 
  ; 
  a 
  seg- 
  

   mental 
  sense 
  organ 
  is 
  also 
  shown 
  in 
  section. 
  Fig. 
  52 
  represents 
  a 
  

   cross-section 
  cutting 
  through 
  the 
  auditory 
  capsule 
  ait, 
  with 
  a 
  segmental 
  

   sense 
  organ, 
  ss, 
  below 
  it; 
  below 
  the 
  pharyngeal 
  region, 
  in 
  the 
  middle 
  

   line, 
  the 
  bulbus 
  arteriosus 
  and 
  ventricle 
  is 
  cut 
  through. 
  Fig. 
  53 
  repre- 
  

   sents 
  a 
  longitudinal 
  section 
  of 
  a 
  young 
  Spanish 
  mackerel 
  somewhat 
  off 
  

   the 
  median 
  line. 
  Above 
  the 
  pericardial 
  cavity 
  pc 
  the 
  branchial 
  and 
  

   hyomaudibular 
  arches 
  are 
  cut 
  across. 
  The 
  heart 
  h 
  opens 
  directly, 
  as 
  in 
  

   fig. 
  56, 
  into 
  the 
  space 
  surrounding 
  the 
  periblast 
  #, 
  as 
  I 
  have 
  elsewhere 
  

   described 
  in 
  the 
  embryo 
  of 
  Clupea. 
  The 
  trabecular 
  cranii 
  ^-are 
  seen 
  to 
  

   be 
  feebly 
  developed 
  at 
  this 
  stage, 
  as 
  shown 
  in 
  both 
  figs. 
  53 
  and 
  56. 
  

   Fig. 
  54 
  represents 
  a 
  cross-section 
  through 
  the 
  pectoral 
  fin 
  fold 
  p', 
  the 
  

   yelk-sack, 
  and 
  segmental 
  ducts 
  sd. 
  The 
  periblast 
  in 
  this 
  section 
  is 
  seen 
  

   to 
  be 
  well 
  developed 
  and 
  contains 
  nuclei. 
  Fig. 
  55 
  represents 
  a 
  cross- 
  

   section 
  through 
  the 
  tail 
  of 
  a 
  young 
  Spanish 
  mackerel, 
  a 
  segmental 
  sense 
  

   organ 
  having 
  also 
  been 
  cut 
  through. 
  Fig. 
  56 
  shows 
  that 
  the 
  oil-drop 
  o, 
  

   at 
  the 
  posterior 
  end 
  of 
  the 
  yelk, 
  is 
  mainly 
  enveloped 
  by 
  the 
  periblast. 
  

   The 
  intestine 
  i 
  is 
  cut 
  through 
  at 
  several 
  points, 
  and 
  the 
  segmental 
  duct 
  

   sd 
  of 
  one 
  side 
  is 
  split 
  lengthwise, 
  the 
  section 
  passing 
  through 
  the 
  urinary 
  

  

  