﻿362 
  ON 
  the 
  basals 
  of 
  eugeniacrinidje. 
  

  

  forms 
  as 
  Eudesicrinus 
  and 
  the 
  somewhat 
  similar, 
  though 
  aberrant, 
  

   Plicatocrinus, 
  show 
  how 
  the 
  basals 
  may 
  have 
  gradually 
  passed 
  up 
  

   into 
  the 
  hollowed 
  aboral 
  end 
  of 
  the 
  radial 
  circlet. 
  A 
  hollow 
  of 
  like 
  

   nature 
  is 
  seen 
  at 
  the 
  aboral 
  end 
  of 
  the 
  calyx 
  in 
  Eugeniacrinus 
  

   Moussoni. 
  These 
  facts 
  afford 
  no 
  positive 
  proof 
  as 
  to 
  the 
  origin 
  of 
  the 
  

   structure 
  in 
  Eugeniacrinus, 
  but 
  they 
  render 
  any 
  comparison 
  of 
  the 
  

   top 
  stem-joint 
  in 
  Eugeniacrinus 
  with 
  the 
  fused 
  basals 
  of 
  Holopus 
  

   valueless 
  as 
  an 
  argument. 
  

  

  The 
  structure 
  above 
  described 
  for 
  Eugeniacrinus 
  is, 
  according 
  to 
  

   v. 
  Zittel 
  *, 
  also 
  found 
  in 
  Phyllocrinus 
  and, 
  with 
  the 
  necessary 
  modi- 
  

   fications 
  due 
  to 
  tetrasymmetry, 
  in 
  Tetracrinus. 
  

  

  The 
  ideas 
  which 
  were 
  thrown 
  out 
  in 
  the 
  concluding 
  paragraph 
  

   of 
  my 
  paper 
  f 
  have 
  received 
  strong 
  support 
  from 
  the 
  conclusions 
  

   contemporaneously 
  arrived 
  at 
  by 
  Messrs. 
  Wachsmuth 
  and 
  Springer 
  % 
  

   in 
  a 
  most 
  important 
  paper, 
  an 
  author's 
  copy 
  of 
  which 
  reached 
  me 
  

   this 
  morning 
  (February 
  19th). 
  While 
  dropping 
  altogether 
  the 
  

   distinction 
  between 
  Paheocrinoidea 
  and 
  Neocrinoidea, 
  they 
  are 
  

   strongly 
  inclined 
  to 
  refer 
  Holopus 
  among 
  other 
  recent 
  genera 
  to 
  

   the 
  Larviformia. 
  With 
  Holopus 
  would 
  naturally 
  go 
  Eudesicrinus 
  

   and 
  Eugeniacrinus. 
  

  

  Discussion. 
  

  

  The 
  President 
  observed 
  that 
  the 
  Author's 
  account 
  of 
  the 
  valuable 
  

   assistance 
  given 
  to 
  him 
  by 
  Prof, 
  von 
  Zittel's 
  kindness 
  was 
  peculiarly 
  

   appropriate 
  on 
  the 
  occasion 
  of 
  Prof. 
  v. 
  Zittel's 
  election 
  as 
  a 
  Foreign 
  

   Member. 
  

  

  Mr. 
  Percy 
  Sladen 
  remarked 
  that 
  the 
  specimens 
  exhibited 
  by 
  

   Mr. 
  Bather 
  were 
  so 
  remarkable, 
  on 
  account 
  of 
  the 
  preservation 
  of 
  

   internal 
  anatomy, 
  that 
  they 
  cut 
  away 
  the 
  ground 
  from 
  the 
  opinions 
  

   which 
  he 
  had 
  previously 
  held. 
  

  

  Dr. 
  Hinde 
  asked 
  how 
  the 
  canals, 
  which 
  now 
  appeared 
  as 
  silicified 
  

   tubes 
  traversing 
  a 
  hollow 
  cavity, 
  had 
  been 
  thus 
  preserved. 
  

  

  The 
  Author, 
  in 
  reply, 
  stated 
  that 
  during 
  life 
  a 
  canal, 
  filled 
  

   only 
  with 
  animal 
  tissue, 
  pierced 
  each 
  solid 
  plate 
  ; 
  the 
  outer 
  layer 
  of 
  

   calcite 
  had 
  been 
  replaced 
  by 
  silica, 
  and 
  the 
  inner 
  portions 
  subse- 
  

   quently 
  removed 
  by 
  weathering 
  and 
  acids. 
  

  

  * 
  Handb. 
  d. 
  Palaont. 
  i. 
  p. 
  386. 
  

  

  t 
  Loc. 
  cit. 
  p. 
  167. 
  

  

  \ 
  " 
  Discovery 
  of 
  the 
  ventral 
  structure 
  of 
  Taxocrinus 
  and 
  Haplocrinus, 
  and 
  

   consequent 
  modifications 
  in 
  the 
  Classification 
  of 
  the 
  Crinoidea," 
  Proc. 
  Acad. 
  

   Nat. 
  Sci. 
  Pbilad. 
  vol. 
  for 
  1888, 
  pp. 
  337-363, 
  pi. 
  xviii. 
  (Philadelphia, 
  1889). 
  

  

  