﻿CLUPEA 
  FROM 
  THE 
  ISLE 
  OF 
  WIGHT. 
  113 
  

  

  delicate 
  concentric 
  ridges 
  may 
  be 
  seen. 
  There 
  are 
  no 
  traces 
  of 
  a 
  

   lateral 
  line. 
  

  

  One 
  of 
  the 
  most 
  striking 
  features 
  in 
  the 
  structure 
  of 
  these 
  fishes 
  

   is 
  the 
  row 
  of 
  strong 
  spines 
  which 
  extends 
  along 
  the 
  ventral 
  margin 
  

   from 
  the 
  pectoral 
  arch 
  to 
  the 
  vent. 
  There 
  are 
  ten 
  or 
  eleven 
  of 
  these 
  

   spines 
  between 
  the 
  pectoral 
  and 
  ventral 
  fins, 
  and 
  ten 
  or 
  eleven 
  be- 
  

   tween 
  the 
  latter 
  and 
  the 
  vent. 
  One, 
  if 
  not 
  more, 
  of 
  the 
  specimens 
  

   shows 
  some 
  of 
  the 
  spines 
  extending 
  in 
  front 
  of 
  the 
  pectoral 
  fins. 
  

   Each 
  of 
  these 
  abdominal 
  spines 
  consists 
  of 
  a 
  horizontal 
  plate, 
  shaped 
  

   like 
  a 
  ploughshare 
  (PL 
  IV. 
  fig. 
  1 
  c), 
  with 
  a 
  free 
  strong 
  point 
  directed 
  

   backwards, 
  supported 
  on 
  each 
  side 
  by 
  a 
  vertical 
  triangular 
  plate, 
  

   strengthened 
  in 
  its 
  middle 
  by 
  a 
  ridge. 
  In 
  fact 
  these 
  spines 
  are 
  similar 
  

   to 
  those 
  found 
  in 
  the 
  Herring 
  and 
  Sprat, 
  but 
  are 
  proportionally 
  

   stronger. 
  In 
  the 
  Herring 
  the 
  median 
  spine 
  and 
  its 
  lateral 
  plates 
  

   are 
  in 
  one 
  piece 
  ; 
  but 
  in 
  these 
  fossils 
  the 
  lateral 
  plates 
  so 
  frequently 
  

   separate 
  from 
  the 
  spine 
  at 
  the 
  same 
  place, 
  as 
  to 
  give 
  the 
  appear- 
  

   ance 
  of 
  a 
  definite 
  division 
  at 
  this 
  point. 
  Two 
  of 
  the 
  larger 
  speci- 
  

   mens 
  have 
  the 
  vertebral 
  column 
  so 
  well 
  preserved 
  that 
  one 
  can 
  

   count 
  in 
  them 
  respectively 
  forty 
  and 
  forty-one 
  vertebras, 
  of 
  which 
  

   fourteen 
  or 
  fifteen 
  are 
  caudal. 
  None 
  of 
  the 
  specimens 
  have 
  the 
  head 
  

   sufficiently 
  perfect 
  to 
  show 
  its 
  precise 
  form 
  ; 
  but 
  the 
  outlines 
  of 
  some 
  

   of 
  the 
  separate 
  bones 
  may 
  be 
  traced, 
  and 
  the 
  close 
  resemblance 
  be- 
  

   tween 
  these 
  and 
  the 
  corresponding 
  parts 
  in 
  the 
  Herring 
  and 
  Sprat 
  

   make 
  it 
  tolerably 
  certain 
  that 
  in 
  the 
  form 
  of 
  the 
  entire 
  head 
  they 
  

   also 
  resembled 
  those 
  fishes. 
  The 
  mandible 
  is 
  deep 
  in 
  proportion 
  to 
  

   its 
  length, 
  and 
  the 
  oral 
  margin 
  nearly 
  vertical 
  and 
  seemingly 
  devoid 
  

   of 
  teeth. 
  Parts 
  of 
  both 
  maxillae 
  are 
  shown 
  in 
  one 
  specimen 
  (fig. 
  1 
  1>), 
  

   and 
  it 
  will 
  be 
  seen 
  that 
  while 
  the 
  proximal 
  end 
  is 
  slender 
  the 
  distal 
  part 
  

   expands 
  into 
  a 
  broad 
  plate, 
  and 
  this 
  is 
  overlapped 
  by 
  an 
  accessory 
  

   maxillary 
  bone 
  of 
  an 
  oval 
  shape, 
  the 
  upper 
  end 
  of 
  which 
  is 
  broken 
  • 
  

   but 
  there 
  can 
  be 
  little 
  doubt 
  that, 
  when 
  perfect, 
  it 
  was 
  continued 
  

   into 
  a 
  slender 
  process 
  forming 
  with 
  the 
  oval 
  plate 
  a 
  battledore- 
  

   shaped 
  bone, 
  as 
  in 
  the 
  Herring. 
  The 
  quadrate 
  bone 
  is 
  shown 
  in 
  

   one 
  specimen, 
  and 
  has 
  very 
  nearly 
  the 
  form 
  of 
  an 
  equilateral 
  

   triangle. 
  The 
  anterior 
  half 
  of 
  the 
  parasphenoid 
  is 
  a 
  slender 
  style, 
  

   widening 
  out 
  where 
  it 
  comes 
  to 
  underlie 
  the 
  brain-case 
  ; 
  but 
  none 
  

   of 
  the 
  specimens 
  show 
  how 
  it 
  terminated 
  posteriorly. 
  The 
  upper 
  

   and 
  lower 
  parts 
  of 
  the 
  preoperculum 
  are 
  nearly 
  at 
  right 
  angles 
  to 
  

   each 
  other 
  (fig. 
  la); 
  the 
  outline 
  of 
  the 
  bone, 
  however, 
  cannot 
  be 
  

   traced. 
  The 
  junction 
  of 
  the 
  operculum 
  with 
  the 
  suboperculum 
  

   forms 
  an 
  oblique 
  and 
  nearly 
  straight 
  line 
  ; 
  not 
  horizontal, 
  as 
  in 
  the 
  

   Pilchard, 
  or 
  sigmoid, 
  as 
  in 
  the 
  Herring. 
  Whitebait, 
  which 
  are 
  said 
  

   to 
  be 
  young 
  Herrings, 
  have 
  the 
  sigmoid 
  curve 
  only 
  slightly 
  marked. 
  

   The 
  gillrakers 
  are 
  long, 
  as 
  shown 
  in 
  the 
  specimen 
  represented 
  by 
  

   figure 
  2. 
  

  

  The 
  bones 
  of 
  the 
  tail 
  (fig. 
  7) 
  are 
  arranged 
  on 
  the 
  same 
  plan 
  as 
  in 
  the 
  

   Herring 
  and 
  Sprat 
  *. 
  The 
  hindermost 
  vertebra 
  is 
  continued 
  up- 
  

   wards 
  and 
  backwards 
  into 
  a 
  style 
  supported 
  by 
  lateral 
  processes 
  ; 
  the 
  

  

  * 
  See 
  Journ. 
  Quekett 
  Club, 
  ser. 
  2, 
  vol. 
  i. 
  p. 
  79 
  (1882). 
  

  

  Q.J.G.S. 
  No. 
  177. 
  i 
  

  

  