﻿4G8 
  Mr. 
  H. 
  B. 
  Preston 
  on 
  

  

  Trachycystis 
  planulata, 
  sp. 
  n. 
  (Fig. 
  13.) 
  ' 
  

  

  Shell 
  depressedly 
  suborbicular, 
  with 
  nearly 
  planulafce 
  spire, 
  

   perforate, 
  thin, 
  horny, 
  pale 
  olivaceous 
  ; 
  whorls 
  4^, 
  rather 
  

   rapidly 
  increasing, 
  the 
  last 
  descending 
  in 
  front, 
  angled 
  at 
  the 
  

   periphery, 
  marked 
  with 
  coarse, 
  oblique, 
  somewhat 
  arcuate, 
  

   transverse 
  riblets 
  ; 
  suture 
  well 
  impressed; 
  base 
  of 
  shell 
  

   slightly 
  convex 
  ; 
  umbilicus 
  moderately 
  wide, 
  deep 
  ; 
  colu- 
  

   mella 
  descending 
  in 
  a 
  very 
  oblique 
  curve; 
  labrum 
  thin, 
  

   narrowly 
  reflexed 
  ; 
  aperture 
  broadly 
  sublunate. 
  

  

  Alt. 
  5*25, 
  diam. 
  maj. 
  11, 
  diam. 
  min. 
  9 
  mm. 
  

  

  Aperture 
  : 
  alt. 
  5, 
  diam. 
  55 
  mm. 
  

  

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

   British 
  East 
  Africa. 
  

  

  Trachycystis 
  pseudocharopa 
  ) 
  sp. 
  n. 
  (Fig. 
  14.) 
  

  

  Shell 
  small, 
  suborbicular, 
  depressed, 
  almost 
  planulate, 
  

   somewhat 
  thin, 
  light 
  brown 
  ; 
  whorls 
  3^, 
  sculptured 
  with 
  

   rather 
  coarse, 
  closely 
  set, 
  oblique, 
  arcuate 
  costulas 
  ; 
  suture 
  

   impressed; 
  umbilicus 
  moderately 
  wide, 
  deep; 
  columella 
  

   vertically 
  descending; 
  labrum 
  simple, 
  acute; 
  aperture 
  

   broadly 
  sublunate. 
  

  

  Alt. 
  1*25, 
  diam. 
  maj. 
  2"5 
  mm. 
  

  

  Hob. 
  Naivasha, 
  British 
  East 
  Africa. 
  

  

  A 
  pretty 
  little 
  species, 
  forcibly 
  reminding 
  one 
  of 
  some 
  of 
  

   the 
  New 
  Zealand 
  and 
  Australian 
  Charopidai. 
  

  

  Trachycystis 
  appros&imans, 
  sp. 
  n. 
  (Fig. 
  15.) 
  

  

  Very 
  closely 
  allied 
  to 
  T. 
  psendocharopa, 
  but 
  differing 
  in 
  its 
  

   much 
  finer 
  sculpture 
  and 
  less 
  depressed 
  form, 
  the 
  present 
  

   species 
  being 
  depressedly 
  turbinate. 
  

  

  Alt. 
  1*5, 
  diam. 
  maj. 
  2*5, 
  diam. 
  min. 
  2 
  mm. 
  

  

  Aperture 
  : 
  alt. 
  '5, 
  diam. 
  about 
  *5 
  mm. 
  

  

  Hab. 
  Between 
  Rumruti 
  and 
  Mount 
  Kenia, 
  British 
  East 
  

   Africa, 
  

  

  Trachycystis 
  rugosa, 
  sp. 
  n. 
  (Fig. 
  16.) 
  

  

  Shell 
  small, 
  depressedly 
  orbicular, 
  covered 
  with 
  a 
  pale 
  

   brown 
  periostracum 
  ; 
  whorls 
  3^, 
  regularly 
  increasing, 
  sculp- 
  

   tured 
  with 
  distant, 
  rather 
  coarse, 
  transverse 
  costulae, 
  between 
  

   which 
  occur 
  fine, 
  closely-set, 
  transverse 
  striae 
  ; 
  suture 
  deeply 
  

   impressed 
  ; 
  base 
  of 
  shell 
  slightly 
  inflated 
  ; 
  umbilicus 
  wide, 
  

   deep 
  ; 
  columella 
  obliquely 
  descending, 
  a 
  callus 
  joining 
  it 
  

   with 
  the 
  lip 
  above; 
  labrum 
  simple; 
  aperture 
  subcircular. 
  

  

  