﻿Analysis 
  of 
  a 
  certain 
  Group 
  of 
  Species 
  of 
  Cyclostoma. 
  63 
  

  

  No. 
  16. 
  More 
  or 
  less 
  reddish, 
  often 
  with 
  a 
  white 
  stripe 
  at 
  the 
  upper 
  edge 
  of 
  

   the 
  last 
  whorl 
  ; 
  with 
  a 
  brown 
  epidermis, 
  which 
  is 
  more 
  or 
  less 
  interrupted 
  by 
  na- 
  

   ked 
  spiral 
  stripes, 
  which 
  are 
  often 
  numerous 
  : 
  wrinkles 
  commencing 
  in 
  some 
  be. 
  

   fore, 
  in 
  others 
  after 
  the 
  end 
  of 
  the 
  penult 
  whorl, 
  in 
  some, 
  narrow 
  and 
  well 
  defined, 
  

   often 
  nearly 
  obsolete, 
  especially 
  on 
  the 
  back 
  of 
  the 
  last 
  whorl 
  ; 
  transverse 
  striae 
  fine 
  

   but 
  rather 
  deep 
  ; 
  rarely 
  a 
  little 
  wrinkled 
  near 
  the 
  umbilical 
  keel, 
  which 
  is 
  well 
  de- 
  

   veloped: 
  spire 
  well 
  elevated 
  : 
  whorls 
  and 
  aperture 
  as 
  in 
  No. 
  15: 
  umbilicus 
  about 
  

   half 
  as 
  wide 
  as 
  the 
  aperture. 
  Operculum 
  with 
  a 
  spiral 
  lamella 
  of 
  si.x 
  or 
  seven 
  

   whorls, 
  moderately 
  sloping 
  outwards, 
  with 
  the 
  upper 
  margin 
  moderately 
  reflected 
  

   externally. 
  

  

  Mean 
  divergence 
  about 
  120° 
  ; 
  height 
  .68 
  inch 
  ; 
  greatest 
  breadth 
  1.04 
  inch; 
  

   least 
  breadth 
  .83 
  inch. 
  

  

  In 
  No. 
  16' 
  the 
  wrinkles 
  are 
  obsolete. 
  

  

  No. 
  16" 
  has 
  the 
  wrinkles 
  mostly 
  on 
  the 
  penult 
  whorl. 
  

  

  No. 
  17. 
  Shell 
  white 
  with 
  more 
  or 
  less 
  reddish, 
  pure 
  white 
  on 
  the 
  last 
  whorl 
  

   next 
  the 
  suture 
  ; 
  with 
  a 
  rich 
  brown 
  epidermis 
  : 
  transverse 
  6tri;e 
  rather 
  coarse 
  ; 
  

   wrinkles 
  minute 
  but 
  well 
  defined, 
  occupying 
  more 
  or 
  less 
  of 
  the 
  last 
  whorl 
  ; 
  um- 
  

   bilical 
  keel 
  well 
  developed 
  : 
  spire 
  much 
  elevated 
  : 
  whorls 
  five 
  and 
  one-third 
  ; 
  last 
  

   V-'horl 
  moderately 
  depressed 
  above 
  ; 
  suture 
  well 
  impressed 
  : 
  aperture 
  large, 
  subor- 
  

   bicular, 
  somewhat 
  acute 
  above 
  ; 
  lip 
  rather 
  thin, 
  slightly 
  sinuated 
  below 
  by 
  the 
  

   umbilical 
  keel 
  : 
  umbilicus 
  half 
  as 
  wide 
  as 
  the 
  aperture. 
  Operculum 
  a 
  little 
  con- 
  

   cave 
  ; 
  spiral 
  lamella 
  with 
  seven 
  or 
  eight 
  whorls, 
  rather 
  wide, 
  curvately 
  reflected, 
  

   but 
  not 
  concealing 
  the 
  intermediate 
  space. 
  

  

  Mean 
  divergence 
  about 
  110°; 
  height 
  .9 
  inch; 
  greatest 
  breadth 
  1.08 
  inch; 
  

   least 
  breadth 
  .87 
  inch. 
  

  

  No. 
  18. 
  Shell 
  white 
  with 
  a 
  greenish 
  brown 
  epidermis, 
  or 
  reddish 
  with 
  a 
  dark 
  

   brown 
  epidermis 
  : 
  with 
  the 
  transverse 
  striae 
  extremely 
  coarse 
  ; 
  with 
  irregular 
  coarse 
  

   but 
  not 
  deep 
  wrinkles 
  on 
  the 
  upper 
  part 
  of 
  the 
  last 
  whorl 
  ; 
  with 
  some 
  more 
  or 
  less 
  

   distinct 
  striae 
  on 
  the 
  last 
  whorl: 
  spire 
  well 
  elevated: 
  whorls 
  about 
  five 
  and 
  one- 
  

   third, 
  scarcely 
  depressed 
  above, 
  with 
  a 
  well 
  impressed 
  suture 
  : 
  aperture 
  large, 
  sub- 
  

   orbicular 
  ; 
  effuse, 
  pointed 
  and 
  advanced 
  above 
  ; 
  lip 
  slightly 
  sinuate 
  above, 
  moder- 
  

   ately 
  thickened 
  ; 
  in 
  the 
  white 
  variety 
  thin 
  and 
  sharp 
  on 
  the 
  right 
  side 
  : 
  umbilicus 
  

   a 
  little 
  more 
  than 
  half 
  as 
  wide 
  as 
  the 
  aperture. 
  Operculum 
  flat 
  ; 
  lamella 
  with 
  six 
  

   or 
  seven 
  distinct 
  whorls, 
  rather 
  narrow, 
  moderately 
  reflected. 
  

  

  Inhabits 
  the 
  middle 
  parts 
  of 
  Manchester. 
  

  

  Mean 
  divergence 
  about 
  120° 
  ; 
  height 
  .88 
  inch 
  ; 
  greatest 
  breadth 
  1.23 
  inch 
  ; 
  

   least 
  breadth 
  1 
  inch. 
  

  

  No. 
  18' 
  is 
  probably 
  an 
  accidental 
  variety, 
  with 
  the 
  last 
  whorl 
  deflected 
  below 
  

   the 
  middle 
  of 
  the 
  penult 
  whorl 
  ; 
  the 
  aperture 
  and 
  the 
  umbilicus 
  are 
  consequently 
  

   contracted 
  : 
  in 
  the 
  other 
  details 
  it 
  agrees 
  with 
  the 
  type. 
  

  

  No. 
  19. 
  Shell 
  white 
  with 
  a 
  brown 
  epidermis 
  : 
  with 
  deep 
  transverse 
  striae 
  ; 
  with 
  

   indistinct 
  spiral 
  striae 
  ; 
  not 
  wrinkled 
  ; 
  umbilical 
  keel 
  obsolete 
  : 
  spire 
  moderately 
  

   elevated 
  : 
  whorls 
  five 
  ; 
  last 
  whorl 
  scarcely 
  depressed 
  above 
  ; 
  suture 
  well 
  impressed 
  : 
  

   aperture 
  suborbicular, 
  effuse, 
  pointed, 
  and 
  advanced 
  above 
  : 
  lip 
  well 
  thickened 
  : 
  

   umbilicus 
  nearly 
  two-thirds 
  as 
  wide 
  as 
  the 
  aperture. 
  Operculum 
  rather 
  concave 
  ; 
  

   lamella 
  with 
  about 
  seven 
  whorls, 
  of 
  medium 
  width, 
  nearly 
  perpendicular 
  except 
  

   that 
  the 
  thickened 
  upper 
  margin 
  is 
  moderately 
  reflected. 
  

  

  