﻿54 
  E. 
  Bose 
  — 
  Ammonoids. 
  

  

  Another 
  specimen 
  of 
  abont 
  7mm. 
  diameter 
  shows 
  still 
  

   greater 
  differences: 
  the 
  shell 
  is 
  in 
  general 
  similar 
  to 
  

   that 
  of 
  the 
  preceding 
  specimen 
  bnt 
  the 
  flanks 
  are 
  more 
  

   rounded, 
  especially 
  on 
  the 
  older 
  half 
  of 
  the 
  external 
  volu- 
  

   tion 
  where 
  the 
  cross-section 
  appears 
  to 
  be 
  nearly 
  semi- 
  

   circular, 
  although 
  the 
  flanks 
  are 
  still 
  a 
  little 
  flatter 
  than 
  

   the 
  well 
  rounded 
  venter. 
  The 
  border 
  of 
  the 
  umbilicus 
  

   shows 
  a 
  sharp 
  edge 
  and 
  the 
  wall 
  is 
  very 
  steep 
  (about 
  75 
  

   degrees). 
  The 
  ornamentation 
  is 
  similar 
  to 
  that 
  of 
  the 
  

   preceding 
  specimen. 
  The 
  cast 
  shows 
  three 
  deep 
  con- 
  

   strictions, 
  nearly 
  radial, 
  but 
  very 
  slightly 
  curved 
  back- 
  

   wards 
  on 
  the 
  flank 
  and 
  more 
  strongly 
  so 
  on 
  .the 
  venter. 
  

  

  The 
  suture 
  is 
  remarkably 
  simple. 
  The 
  ventral 
  lobe 
  is 
  

   broad 
  and 
  divided 
  into 
  two 
  parts 
  by 
  a 
  low 
  siphonal 
  

   saddle, 
  both 
  prongs 
  being 
  still 
  rather 
  sharply 
  pointed 
  in 
  

   the 
  youngest 
  suture 
  of 
  the 
  external 
  whorl 
  and 
  rather 
  

   blunt 
  in 
  the 
  oldest. 
  The 
  first 
  lateral 
  lobe 
  becomes 
  grad- 
  

   ually 
  wider 
  at 
  the 
  end 
  and 
  less 
  pointed 
  at 
  the 
  bottom 
  and 
  

   is 
  nearly 
  as 
  deep 
  as 
  the 
  ventral. 
  The 
  siphonal 
  saddle 
  is 
  

   of 
  pyramidal 
  form, 
  truncated 
  and 
  indented 
  at 
  the 
  front, 
  

   and 
  only 
  one-fourth 
  as 
  high 
  as 
  the 
  external 
  saddle. 
  The 
  

   external 
  saddle 
  becomes 
  more 
  and 
  more 
  round 
  at 
  the 
  end 
  

   and 
  broad 
  at 
  the 
  base, 
  and 
  also 
  more 
  or 
  less 
  symmetrical. 
  

   The 
  first 
  lateral 
  saddle 
  becomes 
  very 
  low 
  and 
  rather 
  

   resembles 
  a 
  broad 
  undulation. 
  

  

  Thus 
  the 
  smallest 
  individual 
  described 
  has 
  all 
  the 
  

   features 
  of 
  Muensteroceras 
  in 
  form 
  as 
  well 
  as 
  in 
  sutures 
  ; 
  

   it 
  seems 
  to 
  resemble 
  especially 
  the 
  young 
  of 
  M. 
  oiveni 
  

   Hall, 
  3 
  although 
  the 
  similarity 
  between 
  its 
  sutures 
  and 
  

   those 
  of 
  M. 
  parallelum 
  Hall, 
  4 
  the 
  type 
  of 
  the 
  genus, 
  is 
  

   rather 
  striking. 
  

  

  The 
  similarity 
  between 
  our 
  new 
  species 
  and 
  Goniolobo- 
  

   ceras 
  ivelleri 
  Smith 
  is 
  so 
  great 
  that 
  there 
  can 
  be 
  scarcely 
  

   any 
  doubt 
  about 
  their 
  being 
  more 
  or 
  less 
  of 
  the 
  same 
  age. 
  

   They 
  certainly 
  belong 
  to 
  a 
  group 
  different 
  from 
  that 
  of 
  

   G. 
  goniolobus. 
  The 
  new 
  species 
  is 
  rather 
  common 
  at 
  the 
  

   locality 
  near 
  Tularosa, 
  our 
  collection 
  containing 
  about 
  

   thirty 
  specimens. 
  Our 
  species 
  is 
  so 
  well 
  characterized 
  

   that 
  we 
  may 
  distinguish 
  it 
  under 
  the 
  name 
  of 
  Goniolobo- 
  

   ceras 
  discoidale 
  n. 
  sp. 
  

  

  Another 
  species 
  of 
  certain 
  importance 
  belongs 
  to 
  the 
  

   genus 
  Gastrloceras. 
  It 
  evidently 
  forms 
  part 
  of 
  the 
  

  

  3 
  J. 
  P. 
  Smith, 
  op. 
  cit., 
  pi. 
  19, 
  figs. 
  5, 
  6. 
  

  

  4 
  J. 
  P. 
  Smith, 
  op. 
  cit., 
  p. 
  121, 
  pi. 
  16, 
  fig. 
  3; 
  pi. 
  19, 
  figs. 
  1-2. 
  

  

  