﻿Dr. 
  H. 
  Ludwig 
  on 
  Ophiopteron 
  elegans. 
  45 
  

  

  collected 
  near 
  Amboyna 
  which, 
  on 
  close 
  examination, 
  ap- 
  

   peared 
  to 
  be 
  a 
  very 
  remarkable 
  new 
  form. 
  The 
  most 
  striking 
  

   thing 
  about 
  it 
  is 
  the 
  circumstance 
  that 
  each 
  joint 
  of 
  the 
  arms 
  

   bears 
  a 
  pair 
  of 
  large 
  fins, 
  which 
  could 
  hardly 
  have 
  any 
  other 
  

   purpose 
  than 
  to 
  confer 
  upon 
  the 
  animal 
  the 
  power 
  of 
  natatory 
  

   locomotion. 
  

  

  Description 
  of 
  the 
  specimen. 
  — 
  The 
  disk 
  has 
  a 
  diameter 
  of 
  

   6 
  millim. 
  Each 
  of 
  the 
  five 
  arms 
  measures 
  about 
  30 
  millim. 
  

   from 
  the 
  margin 
  of 
  the 
  disk 
  to 
  its 
  apex. 
  The 
  colour 
  is 
  a 
  

   uniform 
  light 
  greyish 
  yellow 
  or 
  yellowish 
  white 
  ; 
  only 
  on 
  the 
  

   ventral 
  surface 
  of 
  the 
  disk 
  the 
  coloration 
  in 
  the 
  interradii 
  is 
  

   darker, 
  from 
  brownish 
  yellowish 
  to 
  greyish 
  violet. 
  

  

  The 
  arms 
  at 
  their 
  base 
  are 
  5'5 
  millim. 
  broad, 
  including 
  

   the 
  fins, 
  without 
  the 
  fins 
  scarcely 
  1*5 
  millim. 
  The 
  dorsal 
  

   and 
  ventral 
  scutes 
  have 
  the 
  same 
  breadth 
  of 
  075 
  millim. 
  

   The 
  ventral 
  scutes 
  in 
  the 
  region 
  of 
  the 
  disk 
  are 
  somewhat 
  

   broader 
  than 
  long 
  and 
  scarcely 
  narrower 
  at 
  their 
  proximal 
  

   than 
  at 
  their 
  distal 
  margin 
  ; 
  the 
  latter 
  is 
  slightly 
  emarginate, 
  

   while 
  the 
  lateral 
  margins 
  show 
  a 
  deeper 
  emargi 
  nation 
  ; 
  orally 
  

   from 
  the 
  lateral 
  emargination 
  a 
  short 
  oblique 
  line 
  indicates 
  

   the 
  point 
  of 
  junction 
  of 
  the 
  ventral 
  scute 
  with 
  the 
  lateral 
  

   scute 
  ; 
  the 
  angles 
  which 
  unite 
  the 
  lateral 
  with 
  the 
  distal 
  mar- 
  

   gin 
  are 
  rounded 
  off. 
  In 
  the 
  middle 
  of 
  the 
  length 
  of 
  the 
  arm 
  

   the 
  ventral 
  scutes 
  are 
  considerably 
  narrower 
  at 
  their 
  proximal 
  

   than 
  at 
  their 
  distal 
  margin, 
  the 
  lateral 
  emarginations 
  are 
  no 
  

   longer 
  distinct, 
  but, 
  on 
  the 
  other 
  hand, 
  the 
  oblique 
  lines 
  of 
  

   junction 
  of 
  the 
  ventral 
  scutes 
  with 
  the 
  lateral 
  scutes 
  have 
  

   become 
  comparatively 
  longer. 
  The 
  dorsal 
  scutes 
  in 
  the 
  

   middle 
  division 
  of 
  the 
  arm 
  have 
  on 
  the 
  whole 
  a 
  rounded 
  

   rhombic 
  form 
  ; 
  their 
  greatest 
  breadth 
  is 
  nearer 
  -to 
  their 
  distal 
  

   than 
  to 
  their 
  proximal 
  end 
  ; 
  the 
  two 
  distal 
  sides 
  of 
  the 
  rhom- 
  

   bic 
  form 
  pass 
  into 
  each 
  other 
  in 
  a 
  more 
  broadly 
  rounded 
  

   fashion, 
  the 
  two 
  lateral 
  angles 
  are 
  also 
  rounded 
  off, 
  while 
  the 
  

   proximal 
  angle 
  is 
  transversely 
  truncated 
  ; 
  the 
  median 
  portion 
  

   of 
  the 
  dorsal 
  scute 
  is 
  somewhat 
  more 
  convex 
  than 
  the 
  lateral 
  

   parts, 
  so 
  that 
  a 
  broad 
  but 
  rather 
  low 
  longitudinal 
  keel 
  is 
  

   produced 
  upon 
  the 
  middle 
  of 
  the 
  back 
  of 
  the 
  arm. 
  The 
  lateral 
  

   scutes 
  form 
  upon 
  each 
  side 
  of 
  the 
  arm 
  a 
  high 
  band 
  or 
  plate, 
  

   which 
  commences 
  on 
  the 
  ventral 
  surface 
  of 
  the 
  arm 
  at 
  the 
  

   insertion 
  of 
  the 
  tentacular 
  scale 
  hereafter 
  to 
  be 
  mentioned, 
  

   and, 
  ascending 
  to 
  the 
  dorsal 
  surface 
  in 
  a 
  curved 
  line, 
  extends 
  

   to 
  the 
  proximal 
  part 
  of 
  the 
  lateral 
  margin 
  of 
  the 
  dorsal 
  scutes 
  ; 
  

   this 
  band 
  serves 
  for 
  the 
  insertion 
  of 
  the 
  brachial 
  spines. 
  

  

  The 
  hyaline 
  brachial 
  spines 
  occur 
  in 
  three 
  different 
  forms: 
  — 
  

   1, 
  as 
  hooks; 
  2, 
  as 
  spinulose 
  spines 
  ; 
  3, 
  as 
  the 
  supporting 
  rods 
  

   of 
  the 
  fins. 
  Starting 
  from 
  the 
  dorsal 
  surface 
  of 
  the 
  arm 
  each 
  

  

  