﻿160 
  ilE. 
  E. 
  A. 
  BATHER 
  OX 
  TRIGOXOCRTNTTS 
  FROM 
  

  

  It 
  may, 
  however, 
  be 
  explained 
  on 
  this 
  very 
  principle. 
  In 
  other 
  

   Eugeniacrinidae, 
  notably 
  in 
  E. 
  caryophyllatus, 
  which 
  is 
  the 
  central 
  

   and 
  most 
  abundant 
  species 
  of 
  this 
  family, 
  the 
  body 
  lay 
  in 
  a 
  shallow 
  

   basin 
  on 
  the 
  summit 
  of 
  the 
  first 
  radials, 
  and 
  was 
  protected 
  by 
  the 
  

   overarching 
  second 
  and 
  axillary 
  radials. 
  In 
  the 
  Phylhcrini 
  this 
  

   relation 
  of 
  the 
  soft 
  parts 
  was 
  maintained, 
  but 
  the 
  protection 
  afforded 
  

   by 
  the 
  2nd 
  and 
  3rd 
  radials 
  was 
  obviously 
  less 
  ; 
  there 
  was 
  accordingly 
  

   a 
  tendency 
  to 
  a 
  deepening 
  of 
  the 
  calycal 
  cavity. 
  In 
  Trigonocrinus 
  

   the 
  protection 
  afforded 
  by 
  the 
  free 
  radials, 
  if 
  indeed 
  they 
  existed, 
  

   must 
  have 
  been 
  inappreciable 
  ; 
  accordingly 
  we 
  find 
  the 
  calycal 
  

   cavity 
  sunk 
  right 
  down 
  into 
  the 
  first 
  radials, 
  which 
  are 
  relatively 
  

   elongated 
  and 
  bent 
  in 
  above. 
  Since 
  this 
  was 
  of 
  itself 
  a 
  return 
  to 
  

   primitive 
  conditions, 
  we 
  are 
  at 
  liberty 
  to 
  regard 
  the 
  reappearance 
  

   of 
  basals 
  as 
  a 
  case 
  of 
  correlated 
  reversion. 
  But 
  the 
  very 
  specialized 
  

   character 
  of 
  the 
  calyx, 
  as 
  a 
  whole, 
  renders 
  this 
  explanation 
  rather 
  

   unsatisfactory. 
  Personally, 
  I 
  prefer 
  to 
  explain 
  the 
  change 
  on 
  

   Lamarckian 
  principles 
  : 
  since 
  the 
  viscera 
  sank 
  down 
  between 
  the 
  

   radials, 
  a 
  heavier 
  burden, 
  both 
  literally 
  and 
  metaphorically, 
  was 
  

   thrown 
  on 
  the 
  lower 
  part 
  of 
  the 
  calyx 
  ; 
  the 
  basals 
  could 
  once 
  again 
  

   be 
  of 
  service 
  — 
  consequently, 
  instead 
  of 
  atrophying 
  or 
  becoming 
  

   absorbed, 
  they 
  resumed 
  their 
  old 
  function, 
  and 
  once 
  again 
  formed 
  a 
  

   structural 
  element 
  enclosing 
  a 
  part 
  of 
  the 
  calycal 
  cavity, 
  as 
  in 
  

   Palaeozoic 
  crinoids, 
  and 
  supporting 
  what 
  is 
  in 
  normal 
  crinoids 
  the 
  

   five-chambered 
  organ, 
  which 
  here 
  no 
  doubt 
  had 
  only 
  four 
  chambers, 
  

   and 
  one 
  of 
  those 
  minute. 
  This 
  explanation 
  seems 
  to 
  me 
  so 
  much 
  

   better 
  than 
  the 
  former, 
  that 
  I 
  cannot 
  conceal 
  my 
  regret 
  for 
  the 
  

   adverse 
  criticism 
  it 
  would 
  meet 
  with 
  from 
  the 
  school 
  of 
  biologists 
  at 
  

   present 
  to 
  the 
  fore 
  in 
  England. 
  Is 
  it 
  not, 
  however, 
  possible 
  that 
  

   both 
  causes 
  operated 
  at 
  the 
  same 
  time 
  ? 
  

  

  GrEXERIC 
  AXD 
  SPECIFIC 
  DlAGXOSES. 
  

  

  Such, 
  then, 
  is 
  my 
  interpretation 
  of 
  the 
  structure 
  observed 
  in 
  this 
  

   singular 
  form 
  : 
  and 
  in 
  accordance 
  with 
  this 
  the 
  diagnoses 
  are 
  framed. 
  

   It 
  was 
  necessary 
  that 
  the 
  description 
  of 
  so 
  anomalous 
  a 
  form 
  should 
  

   be 
  full, 
  otherwise 
  there 
  would 
  have 
  been 
  a 
  danger 
  of 
  missing 
  out 
  

   points 
  that 
  future 
  knowledge 
  may 
  prove 
  to 
  be 
  important. 
  Interpre- 
  

   tation 
  was 
  also 
  necessary 
  ; 
  for, 
  even 
  if 
  it 
  prove 
  erroneous, 
  it 
  will 
  

   ensure 
  the 
  correct 
  understanding 
  of 
  the 
  diagnoses. 
  

  

  TRiGoxocRixr/s, 
  gen. 
  nov. 
  

  

  Calyx 
  roughly 
  triangular 
  or 
  trilobate 
  in 
  section. 
  Basals 
  four, 
  

   but 
  one 
  so 
  atrophied 
  as 
  to 
  be 
  almost 
  invisible 
  ; 
  all 
  fused 
  into 
  a 
  basal 
  

   ring. 
  First 
  radials 
  four 
  ; 
  the 
  two 
  on 
  either 
  side 
  of 
  the 
  smallest 
  basal 
  

   half 
  the 
  size 
  of 
  the 
  others, 
  thus 
  maintaining 
  the 
  triangular 
  symmetry 
  ; 
  

   all 
  closely 
  united, 
  with 
  each 
  suture-line 
  in 
  a 
  groove. 
  Processes 
  of 
  

   radials 
  well 
  developed, 
  forming 
  spines 
  homologous 
  with 
  the 
  petals 
  

   of 
  Pliyllocrinus 
  (folioles 
  intermdiaiLv) 
  ; 
  except 
  the 
  adjacent 
  pro- 
  

   cesses 
  of 
  the 
  smaller 
  radials, 
  which 
  only 
  form 
  a 
  minute 
  ridge. 
  

   Articular 
  surface 
  of 
  radials 
  curved 
  gently 
  inwards 
  and 
  upwards 
  ; 
  

  

  