﻿MoIIusca 
  from 
  the 
  North-west 
  Falkland-s. 
  I'M 
  

  

  Tins 
  agglomeration 
  was 
  found 
  spread 
  over 
  a 
  boulder-stone, 
  

   exposed 
  at 
  low 
  tide 
  in 
  tlie 
  upper 
  portion 
  of 
  Roj 
  Cove 
  Creek, 
  

   on 
  January 
  14tli, 
  1910. 
  There 
  must 
  iiava 
  been 
  thousands 
  of 
  

   these 
  little 
  niollusks 
  imbedded 
  thus, 
  for 
  upon 
  removing 
  it 
  

   from 
  the 
  rocks 
  on 
  which 
  it 
  was 
  spread 
  the 
  effect 
  \Aas 
  that 
  of 
  

   little 
  white 
  stars 
  or 
  points 
  of 
  Hght^ 
  sometimes 
  iridescent. 
  

   Miss 
  Wigglesworth, 
  of 
  the 
  Manchester 
  University, 
  has 
  

   kindly 
  examined 
  and 
  analyzed 
  this 
  Algoid 
  mass, 
  and 
  pro- 
  

   nounced 
  it 
  mainly 
  to 
  consist 
  of 
  the 
  cosmopolitan 
  Chlorospeiiu 
  

   alga 
  Enteromorpha 
  compressa, 
  with 
  a 
  species 
  of 
  Conferva, 
  

  

  Cyamionema, 
  subgen. 
  nov. 
  

  

  Cyamium 
  [Cvamionema) 
  decoratum, 
  sp, 
  n, 
  

   (PI. 
  Vll. 
  tigs. 
  5, 
  5 
  a, 
  5 
  b.) 
  

  

  C. 
  testa 
  parva, 
  delicatissima, 
  papyracea, 
  alba, 
  sequivalvi, 
  inaequi- 
  

   laterali, 
  umbonibus 
  coutiguis, 
  margine 
  dorsali 
  recto, 
  vcutrali 
  fere 
  

   parallelo, 
  latere 
  antico 
  rotunda 
  extenso, 
  postice 
  truncatulo, 
  

   superficie 
  concentrice 
  undique 
  irregulariter 
  striata, 
  soepe 
  perio- 
  

   straco 
  tenui 
  olivaceo-straminea 
  induta, 
  ab 
  umbonibus 
  ventralem 
  ad 
  

   marginem 
  centraliter 
  oblique 
  filoso-lirata, 
  lirisnumero 
  7-8, 
  pagina 
  

   intus 
  alba; 
  valva 
  dextra 
  duobus 
  dentibus 
  parvis 
  coutiguis 
  iustructa, 
  

   sinistra 
  uno 
  dentemajore 
  prominulo, 
  lateralibus 
  omnino 
  evanidis, 
  

   ligamento 
  interno 
  uullo, 
  externo 
  perlongOj 
  paUide 
  stramineo, 
  liaea 
  

   palliali 
  Integra. 
  

  

  Alt. 
  3, 
  lat. 
  5 
  mm., 
  sp, 
  max. 
  

  

  Hub. 
  N.W. 
  Falklands, 
  5^6 
  June, 
  1910. 
  

  

  This 
  is 
  a 
  very 
  delicate 
  white 
  shell, 
  of 
  extreme 
  fragility, 
  so 
  

   much 
  so 
  that 
  nearly 
  all 
  the 
  specimens 
  have 
  been 
  fractured 
  

   in 
  the 
  course 
  of 
  microscopical 
  examination. 
  In 
  several 
  

   ways 
  we 
  consider 
  it 
  differs 
  from 
  the 
  normal 
  Cyamium^ 
  

   and 
  justification 
  for 
  the 
  creation 
  of 
  the 
  proposed 
  subgenus 
  

   appears, 
  we 
  think, 
  firstly, 
  in 
  the 
  absence 
  of 
  the 
  internal 
  

   ligament 
  ; 
  secondly, 
  in 
  dental 
  disposition, 
  the 
  right 
  valve 
  

   containing 
  two 
  small 
  contiguous 
  teeth, 
  the 
  left 
  only 
  one, 
  but 
  

   that 
  larger 
  and 
  more 
  conspicuous, 
  the 
  lateral 
  teeth 
  in 
  either 
  

   valve 
  apparently 
  absent 
  altogether 
  ; 
  and, 
  thirdly, 
  in 
  the 
  

   external 
  sculpture, 
  both 
  valves 
  being 
  ornamented, 
  in 
  addition 
  

   to 
  the 
  concentric 
  lines, 
  with 
  seven 
  or 
  eight 
  thread-like 
  lirgs 
  

   proceeding 
  ladiately 
  from 
  the 
  umboes 
  to 
  about 
  the 
  centre 
  of 
  

   the 
  ventral 
  margin. 
  From 
  this 
  circumstance 
  the 
  name 
  Cya^ 
  

   mionema 
  is 
  suggested 
  — 
  Kvdfxiov 
  and 
  vrjfjba, 
  a 
  thread. 
  

  

  We 
  would 
  here 
  especially 
  thank 
  Mr. 
  A. 
  J. 
  Jukes-Brown4>, 
  

   F.R.S., 
  for 
  his 
  examination 
  of 
  this 
  interesting 
  shell 
  and 
  his 
  

   comments 
  thereupon. 
  Several 
  new 
  species 
  of 
  Cyamium 
  have, 
  

   during 
  the 
  past 
  few 
  years, 
  been 
  described 
  by 
  Mr. 
  H. 
  B, 
  

   Preston 
  and 
  others, 
  but 
  none 
  seem 
  comparable 
  with 
  the 
  one 
  

  

  