﻿564 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [76] 
  

  

  EXPLANATION 
  OF 
  PLATE 
  X. 
  

  

  Scomberomorus 
  maculatus. 
  (Spanish 
  Mackerel.) 
  

  

  Fig. 
  46. 
  Cross-section 
  through 
  nasal 
  region 
  of 
  young 
  embryo 
  ; 
  na, 
  nasal 
  pit. 
  x 
  65. 
  

  

  Fig. 
  47. 
  Cross-section 
  through 
  region 
  of 
  the 
  optic 
  cms. 
  x 
  65. 
  

  

  Fig. 
  48. 
  Cross-section 
  through 
  mid-brain, 
  trabecule 
  cranii 
  tr, 
  and 
  eyes, 
  x 
  65. 
  

  

  Fig. 
  49. 
  Section 
  through 
  a 
  segmental 
  sense-organ 
  of 
  the 
  lateral 
  line, 
  x 
  250. 
  

  

  FlG. 
  50. 
  Cross-section 
  through 
  back 
  part 
  of 
  mid-brain, 
  infundibulum, 
  eyes, 
  and 
  optic 
  

   nerves, 
  x 
  65. 
  

  

  Fig. 
  51. 
  Cross-section 
  through 
  fore 
  part 
  of 
  medulla 
  oblongata, 
  x 
  65. 
  

  

  Fig. 
  52. 
  Cross-section 
  through 
  the 
  auditory 
  vesicle 
  au, 
  a 
  segmental 
  sense-organ 
  88, 
  

   front 
  end 
  of 
  chorda, 
  heart, 
  and 
  branchial 
  region, 
  x 
  65. 
  

  

  Fig. 
  53. 
  Longitudinal 
  vertical 
  section 
  through 
  the 
  head 
  of 
  an 
  embryo 
  near 
  the 
  me- 
  

   dian 
  line 
  ; 
  h, 
  heart 
  ; 
  p, 
  periblast 
  ; 
  pc, 
  pericardiac 
  cavity 
  ; 
  tr, 
  cranial 
  trabecula 
  ; 
  

   o, 
  space 
  of 
  oil-drop, 
  x 
  65. 
  

  

  Fig. 
  54. 
  Cross-section 
  through 
  the 
  pectoral 
  region 
  ; 
  sd, 
  segmental 
  duct 
  ; 
  p, 
  periblast 
  ; 
  

   p 
  1 
  , 
  pectoral 
  fin. 
  x 
  65. 
  

  

  Fig. 
  55. 
  Cross-section 
  through 
  the 
  tail. 
  A 
  segmental 
  sense-organ 
  has 
  been 
  cut 
  

   through 
  at 
  one 
  side, 
  x 
  65. 
  

  

  Fig. 
  56. 
  Longitudinal 
  nearly 
  median 
  vertical 
  section 
  through 
  the 
  head, 
  trunk, 
  and 
  

   yelk-sack 
  of 
  an 
  embryo; 
  ch, 
  chorda; 
  m, 
  myotomes; 
  ad, 
  segmental 
  duct 
  ; 
  al, 
  uri- 
  

   nary 
  bladder 
  ; 
  pn, 
  pronephric 
  funnel 
  ; 
  i, 
  intestine 
  ; 
  p, 
  periblast 
  ; 
  o, 
  space 
  oc- 
  

   cupied 
  by 
  oil-drop 
  ; 
  h, 
  heart 
  ; 
  pc, 
  pericardiac 
  cavity 
  ; 
  tr, 
  cranial 
  trabecula. 
  x 
  65. 
  

  

  