﻿OF 
  THE 
  MORAY 
  FIRTH 
  AREA. 
  

  

  265 
  

  

  The 
  above 
  described 
  characters 
  are 
  not 
  those 
  of 
  any 
  part 
  of 
  the 
  

   dermal 
  armature 
  of 
  an 
  Asterolepid, 
  but, 
  on 
  the 
  other 
  hand, 
  clearly 
  

   point 
  to 
  Cosmacanthus 
  being 
  a 
  selachian 
  spine, 
  as 
  was 
  originally 
  

   supposed, 
  though 
  from 
  its 
  want 
  of 
  bilateral 
  symmetry 
  it 
  was 
  in 
  all 
  

   probability 
  a 
  lateral 
  appendage, 
  as 
  in 
  the 
  cases 
  of 
  Oracanthus, 
  

   (iiiracanthus, 
  etc. 
  The 
  identity 
  of 
  the 
  specimen 
  here 
  described 
  

   with 
  Agassiz's 
  type 
  cannot 
  for 
  a 
  moment 
  be 
  doubted 
  ; 
  for 
  that 
  too 
  

   shows 
  the 
  same 
  want 
  of 
  bilateral 
  symmetry, 
  the 
  only 
  difference 
  

   being 
  that 
  the 
  small 
  tubercles 
  on 
  the 
  more 
  convex 
  side 
  show 
  a 
  

   tendency 
  to 
  being 
  arranged 
  in 
  longitudinal 
  rows, 
  like 
  the 
  two 
  

   rows 
  of 
  larger 
  ones 
  along 
  the 
  margin. 
  

  

  The 
  definition 
  of 
  Cosmamnthus 
  will 
  therefore 
  stand 
  : 
  Spines 
  

   much 
  compressed, 
  gently 
  arched, 
  not 
  bilaterally 
  symmetrical, 
  one 
  

   surface 
  being 
  more 
  convex 
  than 
  the 
  other. 
  Free 
  surface 
  orna- 
  

   mented 
  with 
  small 
  stellate 
  tubercles 
  ; 
  posterior 
  area 
  represented 
  

   by 
  a 
  slight 
  groove 
  unsymmetrically 
  placed 
  ; 
  no 
  denticles. 
  It 
  is 
  

   therefore 
  clear 
  that 
  the 
  carboniferous 
  species 
  referred 
  by 
  M'Coy 
  

   and 
  Davis 
  to 
  Cosmamnthus 
  cannot 
  belong 
  here, 
  as 
  they 
  are 
  appa- 
  

   rently 
  ordinary 
  bilaterally-symmetrical 
  dorsal-fin 
  spines. 
  

  

  Fragments 
  of 
  other 
  selachian 
  spines 
  occur 
  in 
  the 
  Scaat 
  Craig 
  

   deposit, 
  but 
  they 
  are 
  not 
  sufficiently 
  perfect 
  to 
  warrant 
  their 
  

   description 
  at 
  the 
  present 
  moment. 
  

  

  Sub-class 
  OS 
  TEA 
  CO 
  DERM 
  I. 
  

   Order 
  ANTIARCHA. 
  

   Family 
  ASTEROLEPIDjE. 
  

  

  Genus 
  BOTERWLEPIS, 
  Agassiz. 
  

   Both 
  riole 
  pis 
  major 
  (Agassi:), 
  1844. 
  

  

  Syn. 
  Pterichthys 
  major, 
  Agassiz 
  ; 
  Placothorax 
  paradoxus, 
  Agassiz 
  ; 
  Both- 
  

   riohpis, 
  tjitjn 
  iitni.<, 
  Tnujnair. 
  

  

  (Restored 
  outline, 
  surface 
  ornament 
  omitted, 
  PI. 
  viii.) 
  

   1 
  Pfa'kMkjft 
  iqfgr' 
  was 
  the 
  name 
  originally 
  given 
  by 
  Agassiz 
  

   (29, 
  p. 
  19, 
  PI. 
  31, 
  figs. 
  1-3) 
  to 
  the 
  base 
  of 
  an 
  arm 
  from 
  Scaat 
  

   Craig, 
  while 
  to 
  other 
  portions 
  of 
  the 
  arm 
  further 
  on 
  he 
  applied 
  

   the 
  name 
  of 
  PUuothorax 
  piradoxus 
  (ib. 
  p. 
  134, 
  PI. 
  30 
  a, 
  figs. 
  

   20-2.5), 
  while 
  portions 
  of 
  the 
  large 
  lnxly 
  plates 
  of 
  the 
  same 
  fish 
  

   from 
  Alves 
  he 
  identified 
  with 
  Eichwald's 
  Bothriolepis 
  ornata 
  

  

  