﻿170 
  ME. 
  P. 
  A. 
  BATHER 
  ON 
  TRIGONOCRINUS 
  FROM 
  

  

  ptter 
  place 
  Dr. 
  Carpenter 
  quotes 
  a 
  few 
  examples 
  from 
  other 
  classes 
  

   of 
  the 
  Echinodermata, 
  and 
  remarks 
  on 
  the 
  same. 
  

  

  A 
  detailed 
  list 
  and 
  a 
  comparison 
  of 
  all 
  known 
  examples 
  of 
  varia- 
  

   tion 
  in 
  symmetry 
  would, 
  it 
  is 
  probable, 
  afford 
  grounds 
  for 
  some 
  

   more 
  definite 
  conclusion 
  ; 
  this 
  would 
  especially 
  be 
  the 
  case 
  if 
  we 
  

   could 
  more 
  often 
  tell 
  which 
  ray 
  was 
  missing 
  or 
  in 
  which 
  inter- 
  

   radius 
  one 
  was 
  added. 
  Some 
  general 
  principle 
  might 
  possibly 
  be 
  

   discovered 
  ; 
  but 
  to 
  attain 
  this 
  desirable 
  end, 
  the 
  cooperation 
  of 
  

   specialists 
  is 
  needed. 
  

  

  EXPLANATION 
  OF 
  PLATE 
  VI. 
  

  

  Fig. 
  1. 
  Trigonocrinus 
  Hratns, 
  specimen 
  A, 
  seen 
  from 
  side 
  of 
  largest 
  basal, 
  en- 
  

   larged. 
  ] 
  a, 
  natural 
  size, 
  outline 
  with 
  spines 
  restored. 
  British 
  Museum 
  

   [E. 
  5502 
  a]. 
  

  

  Fig. 
  2. 
  T. 
  liratus, 
  specimen 
  A, 
  seen 
  from 
  side 
  of 
  smallest 
  basal, 
  enlarged. 
  

   2 
  a, 
  natural 
  size, 
  outline 
  with 
  spines 
  restored. 
  

  

  Fig. 
  3. 
  T. 
  liratus, 
  specimen 
  A, 
  ventral 
  aspect, 
  the 
  largest 
  inter-radius 
  towards 
  

   top 
  of 
  plate 
  ; 
  same 
  scale 
  as 
  figs. 
  1 
  and 
  2. 
  

  

  Fig. 
  4. 
  T. 
  liratus, 
  specimen 
  A, 
  dorsal 
  aspect, 
  showing 
  basal 
  ring, 
  the 
  largest 
  

   basal 
  towards 
  top 
  of 
  plate 
  ; 
  slightly 
  larger 
  scale 
  than 
  figs. 
  1, 
  2, 
  and 
  3. 
  

  

  Fig. 
  5. 
  T. 
  liratus, 
  specimen 
  B, 
  remains 
  of 
  depressions 
  for 
  attachment 
  of 
  arm 
  

   on 
  radial 
  ; 
  compare 
  with 
  figs. 
  8 
  and 
  13. 
  British 
  Museum 
  [E. 
  5502 
  b]. 
  

  

  Fig. 
  6. 
  T. 
  liratus, 
  specimen 
  B, 
  portion 
  of 
  radial 
  surface 
  further 
  enlarged 
  

   (circa 
  30 
  diam.), 
  to 
  show 
  nature 
  of 
  ornament. 
  

  

  Fig. 
  7. 
  T. 
  liratus, 
  plan 
  of 
  dissected 
  calyx 
  from 
  evidence 
  of 
  specimens 
  A 
  and 
  

   B. 
  The 
  basals 
  are 
  repi'esented 
  separately, 
  though 
  they 
  are 
  actually 
  

   fused 
  into 
  a 
  ring 
  ; 
  the 
  two 
  smaller 
  radials 
  are 
  also 
  fused 
  in 
  whole 
  or 
  

   part. 
  

  

  Fig. 
  8. 
  Eugeniacrinus 
  caryophyllatus, 
  calyx 
  supported 
  on 
  the 
  "article 
  basal" 
  

   ( 
  = 
  top 
  stem 
  -joint, 
  mihi). 
  Note 
  clear-cut 
  processes 
  of 
  radials, 
  and 
  well- 
  

   marked 
  depressions 
  for 
  articulation 
  of 
  arms. 
  x2^ 
  diam. 
  After 
  De 
  

   Loriol, 
  Paleont. 
  Franc. 
  T. 
  Jurassique, 
  xi. 
  l 
  e 
  pt. 
  pi. 
  xiii. 
  f. 
  1, 
  b. 
  

  

  Fig. 
  9. 
  E. 
  caryophyllatus, 
  calyx 
  dissected 
  by 
  removal 
  of 
  one 
  radial 
  and 
  the 
  

   halves 
  of 
  the 
  adjacent 
  radials 
  ; 
  shows 
  the 
  radials 
  perforated 
  by 
  canals 
  

   which 
  run 
  from 
  the 
  axial 
  canal 
  to 
  the 
  apertures 
  on 
  the 
  articular 
  ridge. 
  

   X2 
  diam. 
  After 
  Goldfuss, 
  Petref. 
  Deutschlands, 
  pi. 
  1. 
  f. 
  3, 
  d; 
  see 
  

   pp. 
  162-3. 
  The 
  arrangement 
  of 
  the 
  canals 
  harmonizes 
  better 
  with 
  

   Zittel's 
  account 
  than 
  with 
  that 
  of 
  Carpenter, 
  but 
  I 
  cannot 
  vouch 
  for 
  

   its 
  correctness. 
  Note 
  slightness 
  of 
  depression 
  for 
  reception 
  of 
  visceral 
  

   mass 
  as 
  compared 
  with 
  Phyllocrinus 
  and 
  Trigonocrinus. 
  

  

  Fig. 
  10. 
  E. 
  caryophyllatus, 
  dorsal 
  aspect 
  of 
  calyx, 
  shows 
  small 
  axial 
  canal, 
  but 
  

   no 
  trace 
  of 
  basals 
  or 
  of 
  radial 
  canals. 
  X 
  2 
  diam. 
  After 
  Goldfuss, 
  op. 
  

   cit. 
  pi. 
  1. 
  f. 
  3, 
  b. 
  

  

  Fig. 
  11. 
  E. 
  caryophyllatus, 
  same 
  specimen 
  as 
  in 
  fig. 
  8, 
  ventral 
  aspect. 
  x3^ 
  

   diam. 
  After 
  De 
  Loriol, 
  I. 
  c. 
  pi. 
  xiii. 
  f. 
  1, 
  c. 
  

  

  Fig. 
  12. 
  Phyllocrinus 
  fenestratus, 
  Dumortier, 
  sp 
  : 
  , 
  calyx 
  of 
  natural 
  size; 
  note 
  

   long 
  '•' 
  petals 
  " 
  and 
  constricted 
  notches 
  for 
  arms. 
  After 
  De 
  Loriol, 
  I. 
  c. 
  

   pi. 
  xvii. 
  f. 
  6. 
  

  

  Fig. 
  13. 
  P. 
  fenestratus, 
  articular 
  facet 
  of 
  radial 
  from 
  another 
  calyx, 
  enlarged 
  ; 
  

   it 
  is 
  less 
  marked 
  than 
  that 
  of 
  Eugeniacrinus. 
  Alter 
  De 
  Loriol, 
  I. 
  c. 
  

   pi. 
  xvii. 
  f, 
  7, 
  d. 
  

  

  Fig. 
  14. 
  P. 
  granulatus, 
  d' 
  Orb. 
  sp., 
  calyx 
  with 
  petals 
  partly 
  broken. 
  X 
  5 
  diam. 
  

   After 
  De 
  Loriol, 
  I. 
  c. 
  pi. 
  xviii. 
  f. 
  1, 
  a. 
  

  

  Fig. 
  15. 
  P. 
  granulatus, 
  same 
  specimen 
  as 
  in 
  fig. 
  14, 
  ventral 
  aspect 
  ; 
  note 
  small 
  

   articular 
  facet 
  and 
  deeper 
  calycal 
  cavity, 
  thus 
  approaching 
  Trigono- 
  

   crinus. 
  X5 
  diam. 
  After 
  De 
  Loriol, 
  I. 
  c. 
  pi. 
  xviii. 
  f. 
  1, 
  b. 
  

  

  Fig. 
  16. 
  letracrinus 
  moniliformis, 
  Minister, 
  ventral 
  aspect 
  of 
  calyx. 
  x4 
  

   diam. 
  After 
  De 
  Loriol, 
  /. 
  c. 
  pi. 
  xix. 
  f. 
  1, 
  a. 
  

  

  