﻿620 
  MISS 
  DONALD 
  ON 
  SOME 
  NEW 
  SPECIES 
  

  

  sented 
  in 
  the 
  figure 
  of 
  the 
  type 
  species 
  Orthonema 
  Salter 
  I 
  # 
  . 
  Great 
  

   stress 
  cannot 
  be 
  laid 
  on 
  this 
  difference, 
  as 
  the 
  mouth 
  is 
  not 
  well 
  

   drawn, 
  and 
  it 
  may 
  not 
  have 
  been 
  sufficiently 
  well 
  preserved 
  to 
  admit 
  

   of 
  more 
  careful 
  delineation. 
  

  

  Both 
  the 
  Scottish 
  shells 
  are 
  very 
  minute, 
  but 
  they 
  do 
  not 
  differ 
  

   more 
  in 
  size 
  from 
  the 
  type 
  than 
  do 
  some 
  species 
  of 
  Murchisonia 
  

   from 
  one 
  another, 
  and 
  they 
  are 
  about 
  the 
  same 
  size 
  as 
  Orthonema 
  

   sabtceniatum, 
  Geinitz 
  f 
  , 
  one 
  of 
  the 
  smallest 
  species 
  I 
  have 
  seen 
  de- 
  

   scribed. 
  Some 
  of 
  the 
  Spanish 
  species 
  also 
  seem 
  to 
  be 
  very 
  small, 
  

   for 
  Barrois 
  % 
  says 
  that 
  the 
  specimens 
  he 
  has 
  collected 
  of 
  Orthonema 
  

   Ghoffati 
  vary 
  in 
  length 
  from 
  2 
  millim. 
  to 
  20 
  millim., 
  while 
  the 
  

   length 
  of 
  G. 
  Delgado 
  ranges 
  from 
  3 
  centim. 
  to 
  8 
  or 
  9 
  millim. 
  

  

  Orthonema 
  pygm^um, 
  sp. 
  nov. 
  (PI. 
  XX. 
  figs. 
  1, 
  2.) 
  

  

  Shell 
  very 
  minnte, 
  turreted, 
  composed 
  of 
  from 
  seven 
  to 
  nine 
  an- 
  

   gular 
  whorls. 
  Each 
  whorl 
  is 
  ornamented 
  with 
  four 
  keels, 
  and 
  on 
  

   the 
  body- 
  whorl 
  there 
  is 
  an 
  additional 
  fine 
  keel 
  below. 
  The 
  second 
  

   keel 
  from 
  the 
  top 
  is 
  generally 
  the 
  strongest, 
  but 
  sometimes 
  that 
  

   next 
  below 
  is 
  equally 
  strong, 
  the 
  uppermost 
  and 
  the 
  lowest 
  are 
  the 
  

   slightest. 
  The 
  mouth 
  is 
  a 
  little 
  longer 
  than 
  wide, 
  and 
  slightly 
  effuse 
  

   below 
  ; 
  the 
  pillar-lip 
  is 
  thickened 
  and 
  arched 
  forwards. 
  There 
  is 
  no 
  

   evidence 
  of 
  a 
  sinus 
  in 
  the 
  outer 
  lip 
  ; 
  the 
  lines 
  of 
  growth 
  come 
  di- 
  

   rectly 
  down 
  the 
  whorls, 
  merely 
  being 
  deflected 
  by 
  the 
  keels. 
  The 
  

   base 
  is 
  rounded. 
  

  

  Length 
  from 
  2 
  to 
  2 
  J 
  millim. 
  ; 
  width 
  of 
  the 
  body-whorl 
  about 
  1 
  

   millim. 
  

  

  This 
  shell 
  bears 
  a 
  strong 
  resemblance 
  to 
  Orthonema 
  sublamiatum, 
  

   Geinitz 
  §, 
  but 
  differs 
  from 
  it 
  in 
  possessing 
  stronger 
  keels, 
  which 
  divide 
  

   the 
  whorls 
  into 
  unequal 
  spaces 
  ; 
  and 
  also 
  the 
  whorls 
  are 
  not 
  so 
  

   rounded 
  as 
  in 
  that 
  species. 
  

  

  Locality. 
  Glencart, 
  Dairy, 
  Ayrshire. 
  

  

  Formation. 
  Upper 
  Limestone 
  series, 
  which 
  represents 
  the 
  middle 
  

   beds 
  of 
  the 
  Yoredale 
  rocks. 
  

  

  ? 
  Orthonema 
  Youngianum, 
  sp. 
  nov. 
  (PI. 
  XX. 
  figs. 
  3, 
  4.) 
  

  

  Shell 
  small, 
  very 
  elongated, 
  conical, 
  composed 
  of 
  from 
  eleven 
  to 
  

   fourteen 
  whorls. 
  The 
  whorls 
  are 
  closely 
  set, 
  and 
  the 
  outline 
  of 
  the 
  

   spire 
  is 
  somewhat 
  convex. 
  Each 
  whorl 
  is 
  ornamented 
  with 
  three 
  

   or 
  four 
  keels, 
  generally 
  with 
  four, 
  the 
  spaces 
  between 
  them 
  vary 
  in 
  

   width 
  ; 
  in 
  some 
  specimens 
  the 
  two 
  middle 
  keels 
  are 
  the 
  strongest, 
  in 
  

   others 
  only 
  the 
  lower 
  of 
  the 
  two. 
  The 
  mouth 
  is 
  rounded 
  and 
  slightly 
  

   effuse 
  below 
  T 
  , 
  the 
  lip 
  is 
  turned 
  back 
  on 
  the 
  pillar, 
  which 
  is 
  arched 
  

   forward. 
  The 
  base 
  is 
  somewhat 
  flattened 
  and 
  smooth. 
  The 
  lines 
  

  

  * 
  Geol. 
  Surv. 
  Illinois, 
  1866, 
  vol. 
  ii. 
  pi. 
  xxxi. 
  fig. 
  14. 
  

  

  t 
  Dr. 
  H. 
  B. 
  Geinitz, 
  1866. 
  Carbonformation 
  und 
  Dyas 
  in 
  Nebraska, 
  p. 
  12, 
  

   pi. 
  i. 
  fig. 
  18. 
  

  

  X 
  Becherckes 
  sur 
  les 
  Terrains 
  Anciens 
  des 
  Asturies 
  et 
  de 
  la 
  Galice, 
  1883, 
  

   pp. 
  352-354, 
  pi. 
  xvii. 
  figs. 
  21, 
  23. 
  

  

  § 
  Murchisonia 
  subtaniala, 
  H. 
  B. 
  Geinitz, 
  1866, 
  Carbonformation 
  und 
  Dyas 
  

   in 
  Nebraska, 
  p. 
  12, 
  pi. 
  i. 
  fig. 
  18. 
  Orthonema 
  subtceniata, 
  Harden, 
  Final 
  Eeport 
  

   on 
  Nebraska 
  (1871), 
  p. 
  228. 
  

  

  