﻿474 
  Mr. 
  H. 
  B. 
  Preston 
  on 
  

  

  periostracuin 
  ; 
  whorls 
  7, 
  moderately 
  flat, 
  marked 
  only 
  with 
  

   lines 
  of 
  growth 
  ; 
  suture 
  impressed 
  ; 
  columella 
  somewhat 
  

   curved, 
  abruptly 
  truncate 
  ; 
  labium 
  simple, 
  receding 
  below 
  ; 
  

   aperture 
  inversely 
  auriform. 
  

  

  Alt. 
  16*75, 
  diam. 
  maj. 
  4*5 
  mm. 
  

  

  Aperture 
  : 
  alt. 
  4*5, 
  diam. 
  2 
  mm. 
  

  

  Bab. 
  Mount 
  Kenia, 
  6000-8000 
  feet, 
  British 
  East 
  Africa. 
  

  

  Opeas 
  orestias, 
  sp. 
  n. 
  (Fig. 
  30.) 
  

  

  Shell 
  fusiform, 
  yellowish 
  white, 
  thin, 
  rimate, 
  with 
  obtuse 
  

   and 
  rather 
  large 
  apex 
  ; 
  whorls 
  5£, 
  convex, 
  the 
  first 
  one 
  and 
  a 
  

   half 
  smooth, 
  the 
  remainder 
  sculptured 
  with 
  somewhat 
  coarse 
  

   transverse 
  riblets; 
  suture 
  deeply 
  impressed; 
  perforation 
  

   reduced 
  to 
  a 
  mere 
  chink 
  ; 
  columella 
  descending 
  obliquely, 
  

   reflexed 
  ; 
  labrum 
  acute, 
  simple 
  ; 
  aperture 
  elongately 
  ovate. 
  

  

  Alt. 
  4 
  mm., 
  diam. 
  maj. 
  2 
  mm. 
  

  

  Aperture 
  : 
  alt. 
  1, 
  diam. 
  nearly 
  *5 
  mm. 
  

  

  Bab. 
  Mount 
  Kenia, 
  at 
  an 
  altitude 
  of 
  9000-10,000 
  feet, 
  

   British 
  East 
  Africa. 
  

  

  Opeas 
  terebra, 
  sp. 
  n. 
  (Fig. 
  31.) 
  

  

  Shell 
  elongately 
  subulate, 
  shining, 
  yellowish 
  white, 
  thin 
  ; 
  

   whorls 
  10|, 
  the 
  apical 
  whorls 
  smooth, 
  submammillary, 
  the 
  

   remainder 
  flattish, 
  sculptured 
  with 
  fine, 
  transverse, 
  arcuate 
  

   costulai 
  ; 
  suture 
  impressed, 
  rather 
  coarsely 
  crenellated 
  by 
  the 
  

   terminations 
  of 
  the 
  transverse 
  costulse 
  ; 
  columella 
  thickened, 
  

   descending 
  in 
  a 
  slight 
  curve 
  ; 
  labrum 
  white, 
  slightly 
  reflexed 
  ; 
  

   aperture 
  inversely 
  auriform. 
  

  

  Alt. 
  12-5, 
  diam. 
  maj. 
  2"75 
  mm. 
  

  

  Aperture 
  : 
  alt. 
  2*25, 
  diam. 
  1 
  mm. 
  

  

  Bab. 
  Between 
  Rumruti 
  and 
  Mount 
  Kenia, 
  British 
  East 
  

   Africa. 
  

  

  Opeas 
  rumrutiensis, 
  sp. 
  n. 
  (Fig. 
  32.) 
  

  

  Shell 
  rather 
  shortly 
  subulate, 
  thin, 
  semitransparent, 
  wax- 
  

   coloured, 
  with 
  rather 
  blunt 
  apex 
  ; 
  whorls 
  6, 
  slightly 
  convex, 
  

   sculptured 
  with 
  transverse, 
  arcuate, 
  somewhat 
  closely-set 
  

   costulse 
  ; 
  suture 
  impressed, 
  margined 
  below 
  ; 
  columella 
  

   vertically 
  descending, 
  narrowly 
  reflexed; 
  labrum 
  simple; 
  

   aperture 
  inversely 
  auriform. 
  

  

  Alt. 
  G, 
  diam. 
  maj. 
  2, 
  diam. 
  min. 
  1*75 
  mm. 
  

  

  Aperture: 
  alt. 
  1*75, 
  diam. 
  "5 
  mm. 
  

  

  Hob. 
  Between 
  Rumruti 
  and 
  Mount 
  Kenia, 
  British 
  East 
  

   Africa. 
  

  

  