﻿SONNLNIA 
  AND 
  HAMMATOCEKAS. 
  663 
  

  

  mencing 
  the 
  senile 
  stage 
  very 
  early 
  in 
  life. 
  Hamm. 
  anvplectens 
  com- 
  

   mences 
  it 
  still 
  earlier 
  ; 
  its 
  umbilicus 
  is 
  much 
  more 
  closed, 
  the 
  whole 
  

   form 
  is 
  more 
  compressed 
  than 
  in 
  Hamm. 
  amaltheiforme, 
  and, 
  in 
  fact, 
  

   it 
  more 
  truly 
  deserves 
  that 
  trivial 
  name 
  than 
  the 
  species 
  to 
  which 
  it 
  

   is 
  applied. 
  

  

  Bradford 
  Abbas 
  and 
  Louse 
  Hill, 
  Dorset, 
  are 
  the 
  localities 
  from 
  which 
  

   my 
  specimens 
  were 
  obtained. 
  The 
  species 
  occurs 
  in 
  the 
  Concavum- 
  

   zone 
  and 
  is 
  accompanied 
  by 
  Hamm. 
  amaltheiforme, 
  Yacek, 
  Hamm. 
  

   climacomphalum, 
  &c. 
  

  

  EXPLANATION 
  OF 
  PLATE 
  XXII. 
  

  

  Fig. 
  1. 
  Suture-line 
  of 
  a 
  young 
  Pleuroceras 
  pseudocostatum, 
  Hyatt, 
  magnified 
  

   4 
  times. 
  

  

  2. 
  „ 
  Pleuroceras 
  spinatum 
  (Brug.). 
  

  

  3. 
  ,, 
  Pleuroceras 
  subspinatum, 
  S. 
  Buckm. 
  

  

  4. 
  ,, 
  Amaltheus 
  margaritatus, 
  half-grown. 
  

  

  5. 
  „ 
  ,, 
  adult. 
  

  

  6. 
  ,, 
  Sonninia 
  acanthodes, 
  magnified 
  about 
  4 
  times. 
  

  

  7. 
  ,, 
  the 
  same, 
  when 
  larger, 
  to 
  compare 
  with 
  fig 
  1. 
  

  

  Natural 
  size. 
  

  

  8. 
  , 
  , 
  Sonnin 
  ia 
  between 
  S. 
  acanthodes 
  and 
  S. 
  adicra 
  adult. 
  

  

  9. 
  „ 
  Sonninia, 
  sp., 
  to 
  compare 
  with 
  fig. 
  5. 
  

  

  10. 
  „ 
  Sonninia 
  corrugata, 
  Sow., 
  to 
  compare 
  with 
  fig. 
  5. 
  

  

  11. 
  „ 
  Witcliellia 
  Iceviuscula, 
  Sow., 
  spinous. 
  

  

  12. 
  „ 
  Witchellia, 
  sp. 
  

  

  13. 
  ,, 
  Haugia 
  jug 
  osa 
  (Sow.). 
  

  

  14. 
  ,, 
  Haugia 
  Dumortieri, 
  S. 
  Buckm. 
  

  

  15. 
  ,, 
  Haugia 
  Eseri 
  (Oppel). 
  

  

  16. 
  „ 
  Hammatoceras 
  insigne 
  (Schubler). 
  

  

  17. 
  „ 
  young 
  Hammatoceras 
  dolium, 
  n. 
  sp. 
  

  

  18. 
  „ 
  adult 
  Hammatoceras 
  dolium. 
  

  

  19. 
  „ 
  Hammatoceras 
  planinsigne, 
  Yacek. 
  

  

  20. 
  „ 
  Hammatoceras, 
  sp. 
  

  

  21. 
  „ 
  Erycites 
  fallax 
  (Benecke), 
  a 
  genus 
  allied 
  to 
  

  

  Hammatoceras. 
  It 
  shows 
  how 
  the 
  functions 
  of 
  

   the 
  siphonal 
  lobe 
  have 
  been 
  usurped 
  by 
  an 
  inor- 
  

   dinate 
  expansion 
  of 
  the 
  outer 
  portion 
  of 
  the 
  

   superior 
  lateral 
  lobes. 
  This 
  is 
  a 
  characteristic 
  

   of 
  Erycites. 
  Note 
  the 
  contrary 
  condition 
  in 
  

   fig. 
  5 
  (see 
  page 
  656). 
  

  

  22. 
  Inner 
  whorls 
  of 
  Sonninia 
  acanthodes, 
  magnified 
  about 
  12 
  times. 
  

  

  23. 
  „ 
  „ 
  „ 
  „ 
  7 
  „ 
  

  

  Sonninia 
  acanthodes, 
  showing 
  the 
  commencement 
  

   of 
  the 
  spines 
  and 
  the 
  carina 
  and 
  sulcations. 
  

  

  24. 
  „ 
  Witchellia 
  Sutneri 
  magnified, 
  to 
  compare 
  with 
  

  

  fig. 
  22. 
  

  

  25. 
  ,, 
  Amaltheus 
  margaritatus, 
  magnified 
  about 
  4 
  times. 
  

  

  Q. 
  J. 
  G. 
  S. 
  No. 
  180. 
  3 
  c 
  

  

  