﻿64 
  Note 
  on 
  the 
  Genus 
  Stoastoma. 
  

  

  Inhabits 
  the 
  back 
  parts 
  of 
  Manchester. 
  

  

  Mean 
  divergence 
  about 
  130° 
  ; 
  heiglit 
  .53 
  inch 
  ; 
  greatest 
  breadth 
  .77 
  inch 
  ; 
  least 
  

   breadth 
  .62 
  inch. 
  

  

  No. 
  20. 
  Shell 
  white, 
  reddish 
  on 
  the 
  upper 
  whorls, 
  with 
  a 
  pale 
  greenish 
  brown 
  

   epidermis 
  : 
  transverse 
  striae 
  very 
  fine, 
  wrinkled 
  ; 
  with 
  minute 
  wrinkles 
  nearly 
  cov- 
  

   ering 
  the 
  last 
  whorl 
  ; 
  umbilical 
  keel 
  wanting 
  : 
  spire 
  moderately 
  elevated 
  : 
  whorls 
  

   five 
  ; 
  last 
  whorl 
  flattened 
  beneath, 
  making 
  the 
  periphery 
  subangular 
  ; 
  with 
  the 
  

   suture 
  well 
  impressed 
  : 
  aperture 
  suborbicular 
  ; 
  efflise, 
  pointed, 
  and 
  much 
  advanced 
  

   above 
  ; 
  lip 
  thick 
  : 
  umbilicus 
  half 
  as 
  wide 
  as 
  the 
  aperture. 
  Operculum 
  unknown. 
  

  

  Mean 
  divergence 
  about 
  130° 
  ; 
  height 
  .45 
  inch 
  ; 
  greatest 
  breadth 
  .7 
  inch 
  ; 
  least 
  

   breadth 
  .58 
  inch. 
  

  

  Note 
  on 
  the 
  genus 
  Stoastoma. 
  Following 
  the 
  sugges- 
  

   tion 
  of 
  Dr. 
  PfeifFer, 
  (Zeitschr. 
  Malak. 
  1849, 
  p. 
  113,) 
  I 
  recog- 
  

   nize 
  the 
  genus 
  Stoastoma 
  in 
  the 
  well-known 
  Cyclostoma 
  sue- 
  

   cineum 
  Soivb. 
  It 
  appears 
  to 
  me, 
  however, 
  that 
  Dr. 
  P. 
  has 
  

   gone 
  too 
  far 
  in 
  saying 
  that 
  this 
  species 
  may 
  be 
  taken 
  as 
  the 
  

   chief 
  type 
  ('* 
  Haupttypus 
  ") 
  of 
  the 
  new 
  genus. 
  It 
  differs 
  from 
  

   all 
  the 
  species 
  of 
  Jamaica, 
  in 
  having 
  the 
  labrum 
  sharp 
  and 
  not 
  

   produced 
  beyond 
  the 
  labium, 
  in 
  the 
  manner 
  which 
  suggested 
  

   the 
  name 
  of 
  the 
  genus. 
  Stoastoma 
  succineum 
  might 
  there- 
  

   fore 
  be 
  considered 
  as 
  the 
  type 
  of 
  a 
  Polynesian 
  subgenus, 
  

   which 
  has 
  about 
  the 
  same 
  degree 
  of 
  affinity 
  to 
  Stoastoma 
  

   proper, 
  that 
  Partula 
  has 
  to 
  Bulimus. 
  

  

  Stoastoma 
  ViLKiNSONiiE. 
  Shell 
  subdiscoidal 
  : 
  pale 
  horn 
  

   color, 
  subtransparent 
  : 
  with 
  five 
  spiral 
  carinse, 
  of 
  which 
  one 
  

   runs 
  into 
  the 
  suture, 
  and 
  one 
  appears 
  on 
  the 
  middle 
  of 
  the 
  

   whorls 
  of 
  the 
  spire 
  ; 
  some 
  have, 
  in 
  place 
  of 
  the 
  last 
  one, 
  two 
  

   smaller 
  carinse 
  ; 
  with 
  very 
  delicate 
  spiral 
  raised 
  lines, 
  usually 
  

   four 
  to 
  six 
  in 
  each 
  interspace 
  : 
  spire 
  moderately 
  and 
  convexly 
  

   elevated 
  : 
  whorls 
  three 
  and 
  one-half, 
  angulated, 
  with 
  a 
  deep 
  

   suture 
  ; 
  last 
  whorl 
  rather 
  large, 
  detached 
  from 
  the 
  penult 
  

   whorl 
  near 
  the 
  aperture 
  : 
  aperture 
  campanulate 
  ; 
  labrum 
  pro- 
  

   duced 
  very 
  far, 
  above 
  abruptly 
  produced 
  and 
  auriculate, 
  with 
  

   wide 
  and 
  deep 
  scallops 
  formed 
  by 
  the 
  produced 
  carinas 
  ; 
  labi- 
  

   um 
  much 
  detached 
  from 
  the 
  penult 
  whorl 
  and 
  a 
  little 
  reflect- 
  

  

  