﻿ANNIVERSARY 
  ADDRESS 
  OF 
  THE 
  PRESIDENT. 
  xlv 
  

  

  to 
  the 
  genus 
  Cidaris 
  ; 
  but 
  none 
  of 
  the 
  genera 
  are 
  truly 
  palaeozoic. 
  

   Of 
  the 
  Brachiopoda 
  there 
  are 
  45 
  species 
  and 
  6 
  genera, 
  namely, 
  Tere- 
  

   bratula, 
  Rhynchonella, 
  Spirifer, 
  Orthis, 
  Productus, 
  and 
  Crania. 
  Four 
  

   of 
  these 
  are 
  essentially 
  of 
  palaeozoic 
  types 
  ; 
  and 
  the 
  genera 
  Terebratula 
  

   and 
  Rhynchonella, 
  of 
  which 
  there 
  are 
  30 
  species, 
  may 
  be 
  considered 
  

   as 
  typical 
  of 
  both 
  epochs, 
  although 
  perhaps, 
  as 
  regards 
  mere 
  quan- 
  

   tity, 
  more 
  common 
  in 
  mesozoic 
  than 
  in 
  palaeozoic 
  times. 
  Of 
  the 
  

   Lamellibranchiate 
  Monomyaria 
  there 
  are 
  8 
  genera 
  and 
  Q5 
  species, 
  

   2 
  of 
  these 
  belonging 
  to 
  the 
  palaeozoic 
  genus 
  Posidonomya 
  ; 
  and 
  of 
  

   15 
  genera 
  and 
  68 
  species 
  of 
  Dimyaria, 
  5 
  of 
  the 
  genera 
  (including 
  

   32 
  species 
  of 
  Mytilus, 
  Modiola, 
  Area, 
  Nueula, 
  and 
  Myophoria) 
  are 
  

   both 
  palaeozoic 
  and 
  secondary. 
  The 
  only 
  Heteropod, 
  Porcellia, 
  is 
  of 
  

   a 
  palaeozoic 
  genus 
  ; 
  and 
  of 
  the 
  27 
  genera 
  (some 
  of 
  them 
  doubtful) 
  

   and 
  352 
  species 
  of 
  Gasteropoda, 
  4 
  genera, 
  namely, 
  Natica 
  30 
  species, 
  

   Trochus 
  36 
  species, 
  Schizostoma 
  5 
  species, 
  and 
  Pleurotomaria 
  46 
  spe- 
  

   cies, 
  are 
  both 
  palaeozoic 
  and 
  secondary. 
  

  

  Of 
  Cephalopoda 
  there 
  are 
  said 
  to 
  be 
  6 
  genera 
  and 
  89 
  species, 
  namely, 
  

   Goniatites 
  4, 
  Ceratites 
  1, 
  Ammonites 
  75, 
  Nautilus 
  1, 
  ConcJiorhyn- 
  

   chus 
  1, 
  and 
  Orthoceras 
  7. 
  Two 
  of 
  these 
  genera 
  — 
  Goniatites 
  and 
  Or- 
  

   thoceras 
  — 
  are 
  essentially 
  palaeozoic 
  forms 
  ; 
  the 
  genus 
  Nautilus 
  is 
  of 
  

   both 
  ages 
  ; 
  one, 
  the 
  Conchorhynchus, 
  is 
  peculiar 
  ; 
  and 
  the 
  other 
  two 
  

   are 
  secondary 
  forms. 
  The 
  few 
  remaining 
  Articulata, 
  Crustacea, 
  and 
  

   Fish 
  may 
  be 
  said 
  to 
  be 
  secondary 
  forms. 
  The 
  number 
  of 
  species 
  

   altogether 
  is 
  probably 
  greatly 
  exaggerated 
  ; 
  but, 
  supposing 
  the 
  ex- 
  

   aggeration 
  to 
  be 
  about 
  equal 
  in 
  all 
  the 
  classes 
  and 
  genera, 
  the 
  pro- 
  

   portions 
  would 
  remain 
  about 
  the 
  same; 
  and 
  the 
  result 
  would 
  be 
  

   that, 
  out 
  of 
  104 
  genera, 
  15 
  are 
  characteristically 
  palaeozoic 
  and 
  

   11 
  are 
  mixed. 
  Thus, 
  out 
  of 
  774 
  species, 
  44 
  belong 
  to 
  the 
  15 
  genera 
  

   mentioned 
  as 
  characteristically 
  palaeozoic, 
  while 
  the 
  11 
  genera 
  that 
  

   occur 
  both 
  in 
  palaeozoic 
  and 
  secondary 
  rocks 
  yield 
  180 
  species, 
  

   perhaps 
  every 
  one 
  of 
  which 
  is 
  confined 
  to 
  the 
  St. 
  Cassian 
  beds. 
  The 
  

   broad 
  generalization 
  from 
  this 
  is, 
  that 
  T 
  th 
  of 
  the 
  genera 
  and 
  nearly 
  

   -1-th 
  of 
  the 
  species 
  have 
  a 
  common 
  palaeozoic 
  facies. 
  

  

  Again, 
  if 
  we 
  take 
  Minister's 
  determination, 
  we 
  find 
  that 
  he 
  gives 
  

   a 
  list 
  and 
  drawings 
  of 
  

  

  Corals 
  

  

  . 
  14 
  1 
  

  

  genera 
  

  

  , 
  53 
  s 
  

  

  aeci 
  

  

  Echinodermata 
  

  

  4 
  

  

  )j 
  

  

  35 
  

  

  )> 
  

  

  Brachiopoda 
  

  

  5 
  

  

  >f 
  

  

  27 
  

  

  a 
  

  

  Lamellibranchiata 
  . 
  

  

  . 
  18 
  

  

  >> 
  

  

  72 
  

  

  )> 
  

  

  Gasteropoda 
  

  

  . 
  26 
  

  

  ?» 
  

  

  191 
  

  

  }) 
  

  

  Cephalopoda 
  

  

  6 
  

  

  a 
  

  

  33 
  

  

  }i 
  

  

  Fish 
  

  

  4 
  

  

  }) 
  

  

  5 
  

  

  it 
  

  

  Reptiles 
  

  

  1 
  

  

  it 
  

  

  1 
  

  

  3> 
  

  

  78 
  417 
  

  

  Of 
  these, 
  8 
  genera 
  and 
  29 
  species 
  belong 
  to 
  palaeozoic 
  types, 
  and 
  13 
  

   genera 
  (including 
  104 
  species) 
  are 
  mixed. 
  This 
  gives 
  very 
  nearly 
  

   y^th 
  of 
  the 
  genera 
  and 
  between 
  yyth 
  and 
  y^-th 
  of 
  the 
  species 
  as 
  

   belonging 
  to 
  types 
  characteristically 
  palaeozoic 
  ; 
  and 
  of 
  these, 
  accord- 
  

   vol, 
  xx, 
  e 
  

  

  