﻿ANNIVERSARY 
  ADDRESS 
  OF 
  THE 
  PRESIDENT. 
  233 
  

  

  "Pterocera 
  oceanic 
  At 
  least 
  20 
  species 
  of 
  Harpoceras 
  occur 
  in 
  the 
  

   Upper 
  Lias 
  of 
  Britain, 
  and 
  4 
  in 
  the 
  Inferior 
  Oolite. 
  Harpoceras 
  

   cannot 
  be 
  mistaken 
  for 
  any 
  other 
  genus 
  ; 
  the 
  ventral 
  area 
  is 
  always 
  

   keeled 
  ; 
  the 
  sides 
  of 
  the 
  shell 
  ornamented 
  with 
  falciform 
  ribs 
  ; 
  mouth- 
  

   border 
  sickle-shaped, 
  with 
  lateral 
  auricles 
  or 
  expansions, 
  and 
  a 
  long 
  

   pointed 
  rostrum-like 
  ventral 
  process. 
  Many 
  other 
  characters 
  I 
  

   cannot 
  here 
  describe. 
  

  

  The 
  Upper-Lias 
  species 
  of 
  Harpoceras 
  are 
  : 
  — 
  

  

  Harpoceras 
  falciferum. 
  

  

  serpentinum. 
  

  

  bifrons. 
  

  

  lythense. 
  

  

  ■ 
  variabile. 
  

  

  ovatum. 
  

  

  Levisoni. 
  

  

  Beanii. 
  

  

  elegans. 
  

  

  opalinum. 
  

  

  Harpoceras 
  insigne. 
  

  

  radians. 
  

  

  striatulum. 
  

  

  concavum. 
  

  

  aalense. 
  

  

  thouarsense. 
  

  

  primordiale. 
  

  

  subconcavum. 
  

  

  exaratum. 
  

  

  The 
  Harpocerata 
  from 
  the 
  Inferior 
  Oolite 
  are 
  : 
  — 
  

  

  Harpoceras 
  Murchisonae. 
  Harpoceras 
  Sowerbyii. 
  

   Tessonianum. 
  Edwardianurn. 
  

  

  Genus 
  Oppelia, 
  Waagen. 
  — 
  A 
  rare 
  genus 
  in 
  the 
  British 
  Islands, 
  

   which 
  first 
  occurs 
  in 
  the 
  Inferior 
  Oolite. 
  In 
  India 
  many 
  species 
  have 
  

   been 
  described 
  by 
  Dr. 
  Waagen. 
  The 
  " 
  Golden 
  Oolite 
  " 
  of 
  Keera 
  

   Hill, 
  Kutch, 
  and 
  other 
  higher 
  strata 
  have 
  yielded 
  a 
  rich 
  harvest 
  of 
  

   species 
  of 
  Oppelia. 
  The 
  most 
  characteristic 
  British 
  forms 
  are 
  0. 
  

   subradiata, 
  Sow., 
  and 
  0. 
  discus, 
  Sow. 
  ; 
  the 
  latter 
  is 
  a 
  Cornbrash 
  

   species. 
  Oppelia 
  has 
  a 
  wide 
  stratigraphical 
  range, 
  from 
  the 
  lower 
  

   to 
  the 
  uppermost 
  stages 
  of 
  the 
  Jurassic 
  series 
  ; 
  it 
  is 
  also 
  Neocomian 
  

   and 
  Upper 
  Cretaceous. 
  

  

  Genus 
  Haploceras, 
  Zittel. 
  — 
  Separated 
  from 
  Oppelia 
  by 
  marked 
  

   characters 
  : 
  well-defined 
  lines 
  of 
  growth 
  and 
  narrow 
  umbilicus, 
  no 
  

   bifurcation 
  of 
  ribs, 
  no 
  keel 
  or 
  channel 
  in 
  the 
  siphonal 
  area, 
  with 
  

   peculiar 
  conditions 
  of 
  the 
  lobes, 
  serve 
  to 
  distinguish 
  this 
  genus. 
  

   The 
  group 
  Ligati, 
  D'Orb., 
  in 
  part 
  belongs 
  here. 
  The 
  Inferior-Oolite 
  

   forms 
  Hapl. 
  ooliticum, 
  D'Orb., 
  and 
  Hapl. 
  ligatum, 
  D'Orb., 
  are 
  

   examples 
  of 
  the 
  species. 
  

  

  Subfam. 
  3. 
  StepTianoceratites. 
  

  

  Genus 
  Stephanoceras. 
  — 
  The 
  species 
  of 
  this 
  large 
  genus 
  are 
  essen- 
  

   tially 
  Lower 
  Jurassic. 
  They 
  commence 
  in 
  the 
  Upper 
  Lias 
  with 
  

   S. 
  commune, 
  S. 
  annulatum, 
  S. 
  crassum, 
  S. 
  Holandrei, 
  S, 
  jibula- 
  

   tum, 
  &c. 
  The 
  base 
  of 
  the 
  Inferior 
  Oolite 
  teems 
  with 
  individuals 
  ; 
  

   and 
  both 
  in 
  France 
  and 
  England 
  the 
  zone 
  of 
  S. 
  Humphriesianum 
  is 
  

   the 
  home 
  for 
  numerous 
  forms. 
  The 
  species 
  in 
  Yon 
  Buch's 
  groups 
  

   xviii. 
  (the 
  Planulati), 
  xix. 
  (the 
  Coronarii), 
  and 
  xx. 
  (the 
  Macroce- 
  

   phali) 
  have 
  been 
  partly 
  absorbed 
  recently 
  into 
  the 
  genus 
  Ste- 
  

   phanoceras. 
  This 
  is 
  at 
  once 
  manifest 
  from 
  the 
  following 
  list 
  of 
  

   species 
  : 
  — 
  

  

  vol. 
  xxxvni. 
  s 
  

  

  