﻿624 
  MISS 
  DONALD 
  ON 
  SOME 
  NEW 
  SPECIES 
  

  

  Muechisonia. 
  (Stegocozlia) 
  compacta, 
  sp. 
  nov. 
  (PI. 
  XX. 
  figs. 
  9-13.) 
  

  

  Shell 
  small, 
  short 
  and 
  conical, 
  composed 
  of 
  from 
  six 
  to 
  nine 
  

   ■whorls. 
  The 
  whorls 
  are 
  almost 
  convex, 
  being 
  but 
  slightly 
  angular. 
  

   A 
  little 
  above 
  the 
  centre 
  of 
  each 
  whorl 
  there 
  is 
  a 
  strong 
  keel, 
  below 
  

   which 
  there 
  is 
  another 
  almost 
  equally 
  strong, 
  and 
  just 
  above 
  the 
  

   suture 
  there 
  is 
  a 
  third 
  and 
  slighter 
  keel 
  ; 
  the 
  space 
  between 
  the 
  

   two 
  uppermost 
  is 
  the 
  greatest. 
  Below 
  the 
  suture 
  there 
  are 
  two 
  

   very 
  fine 
  keels 
  placed 
  close 
  together, 
  occupying 
  about 
  half 
  of 
  the 
  

   upper 
  surface 
  of 
  the 
  whorl 
  and 
  leaving 
  a 
  wide 
  space 
  between 
  them 
  

   and 
  the 
  strongest 
  keel. 
  This 
  space 
  seems 
  to 
  have 
  been 
  formed 
  by 
  

   the 
  successive 
  filling 
  up 
  of 
  the 
  sinus 
  in 
  the 
  outer 
  lip, 
  as 
  indicated 
  

   by 
  the 
  lines 
  of 
  growth, 
  which 
  are 
  strongly 
  arched 
  and 
  so 
  fine 
  that 
  

   they 
  are 
  only 
  to 
  be 
  observed 
  on 
  well-preserved 
  specimens. 
  On 
  the 
  

   rest 
  of 
  the 
  shell 
  the 
  lines 
  of 
  growth 
  are 
  much 
  stronger 
  and 
  may 
  

   be 
  distinctly 
  seen 
  curving 
  back 
  over 
  the 
  two 
  uppermost 
  keels 
  and 
  

   curving 
  forward 
  again 
  below 
  the 
  strongest 
  keel. 
  Base 
  of 
  the 
  shell 
  

   rounded. 
  Mouth 
  rather 
  longer 
  than 
  wide, 
  slightly 
  channelled 
  below 
  ; 
  

   outer 
  lip 
  reflected 
  over 
  the 
  pillar 
  ; 
  the 
  inner 
  lip 
  is 
  a 
  thin 
  shelly 
  

   layer 
  spread 
  on 
  the 
  columella 
  ; 
  it 
  thickens 
  at 
  the 
  base 
  of 
  the 
  pillar 
  

   and 
  covers 
  the 
  umbilicus 
  in 
  adult 
  specimens, 
  in 
  young 
  ones 
  the 
  

   umbilicus 
  is 
  open. 
  

  

  Length 
  of 
  a 
  medium-sized 
  specimen 
  about 
  -i 
  millim., 
  width 
  of 
  

   body-whorl 
  2 
  millim. 
  A 
  fragment 
  of 
  a 
  larger 
  specimen 
  measures 
  

   2| 
  millim. 
  across 
  the 
  body-whorl, 
  height 
  of 
  its 
  body-whorl 
  2| 
  

   millim. 
  

  

  This 
  shell 
  is 
  shorter 
  than 
  is 
  the 
  case 
  in 
  most 
  of 
  the 
  Murchisonice. 
  

   Its 
  ornamentation 
  resembles 
  that 
  of 
  M. 
  quadricarinata, 
  M 
  c 
  Coy, 
  but 
  

   it 
  may 
  easily 
  be 
  distinguished 
  from 
  that 
  shell 
  by 
  its 
  greater 
  spiral 
  

   angle 
  and 
  smaller 
  number 
  of 
  whorls. 
  It 
  appears 
  to 
  be 
  identical 
  with 
  

   some 
  shells 
  in 
  the 
  Brussels 
  Museum 
  from 
  Vise 
  marked 
  M. 
  spirata, 
  

   Goldf.* 
  I 
  have, 
  however, 
  seen 
  the 
  type 
  of 
  this 
  species 
  in 
  the 
  Bonn 
  

   Museum, 
  and 
  it 
  is 
  a 
  totally 
  different 
  shell, 
  being 
  more 
  elongated, 
  

   and 
  the 
  ornamentation 
  is 
  quite 
  distinct. 
  

  

  Locality. 
  Glencart, 
  Dairy. 
  

  

  Formation. 
  Upper 
  Limestone 
  Series. 
  

  

  There 
  is 
  a 
  single 
  specimen 
  of 
  this 
  species 
  in 
  the 
  Jermyn 
  Street 
  

   Museum, 
  marked 
  Xo. 
  TK, 
  1(518. 
  It 
  is 
  well 
  preserved 
  and 
  consists 
  

   of 
  six 
  whorls, 
  the 
  apex 
  is, 
  however, 
  broken 
  : 
  if 
  entire 
  there 
  would 
  

   probably 
  be 
  two 
  or 
  three 
  more 
  whorls. 
  One 
  of 
  the 
  fine 
  keels 
  on 
  the 
  

   upper 
  part 
  of 
  the 
  whorl 
  is 
  wanting 
  in 
  this 
  specimen. 
  This 
  may 
  

   perhaps 
  arise 
  from 
  the 
  substance 
  in 
  which 
  the 
  shell 
  is 
  preserved 
  being 
  

   too 
  coarse 
  to 
  retain 
  it. 
  

  

  Length 
  3 
  millim., 
  width 
  of 
  body- 
  whorl 
  1| 
  millim. 
  

  

  Locality. 
  Cawledge 
  Burn, 
  § 
  of 
  a 
  mile 
  X. 
  of 
  Cawledge 
  Park, 
  S. 
  of 
  

   Alnwick. 
  

  

  Formation. 
  About 
  the 
  same 
  horizon 
  as 
  the 
  Yoredale 
  rocks 
  t. 
  

  

  * 
  Petr. 
  Germ 
  vol. 
  iii. 
  p. 
  26, 
  pi. 
  172. 
  fig. 
  6, 
  a, 
  b. 
  

  

  t 
  I 
  am 
  greatly 
  indebted 
  to 
  Mr. 
  John 
  Young, 
  Hunterian 
  Museum, 
  Glasgow, 
  for 
  

   bis 
  kindness 
  in 
  giving 
  me 
  every 
  facility, 
  whilst 
  writing 
  this 
  paper, 
  for 
  studying 
  

   his 
  fine 
  collection 
  of 
  Carboniferous 
  Gasteropoda 
  and 
  also 
  for 
  the 
  gift 
  of 
  many 
  

   specimens. 
  

  

  