﻿BIHANG 
  TILL 
  K. 
  SV. 
  VET.-AKAD. 
  HANDL. 
  BaKD 
  6. 
  N:0 
  21. 
  27 
  

  

  Helsingfors, 
  Visby, 
  Klintehamn. 
  

   var. 
  exilis 
  (Kutz.) 
  Grun. 
  

   VH. 
  D. 
  B. 
  Pl. 
  VIII, 
  fig. 
  2. 
  

   Helsingfors. 
  

  

  jV. 
  Thurholmensis 
  nov. 
  spec. 
  

  

  Plate 
  I, 
  fig. 
  11. 
  

  

  Valve 
  lanceolate, 
  with 
  produced, 
  capitate 
  ends. 
  Striae 
  

   very 
  fine, 
  26 
  in 
  0,01 
  mm., 
  transversal, 
  reacliing 
  tlie 
  median 
  line. 
  

  

  Belongs 
  to 
  the 
  group 
  of 
  Nav. 
  cryptocephala 
  and 
  seems 
  

   to 
  stånd 
  nearest 
  to 
  N. 
  gregaria 
  Donk., 
  but 
  diiFers 
  by 
  the 
  

   capitate 
  ends 
  and 
  the 
  fine, 
  quite 
  transversal 
  striae. 
  

  

  Very 
  rare: 
  At 
  Thurholm 
  near 
  Helsingfors. 
  

  

  JV. 
  arenaria 
  DoNK. 
  

  

  VH. 
  D. 
  B. 
  Pl. 
  VIII, 
  fig. 
  18. 
  

  

  Sölvesborg, 
  Karlshamn. 
  

  

  N. 
  divergens 
  Sm. 
  

  

  Gotland: 
  Klintehamn, 
  a 
  linear 
  form 
  with 
  broad, 
  rounded 
  

   extremities. 
  Plate 
  II, 
  fig. 
  13. 
  

  

  N. 
  limosa 
  K. 
  

  

  VH. 
  D. 
  B. 
  Pl. 
  XII, 
  fig. 
  18. 
  

  

  Gotland: 
  Slite 
  (Cl.), 
  Södertelje 
  (Cl.), 
  Rathan 
  (Cl.). 
  

  

  N. 
  ventricosa 
  Donk. 
  

  

  Donk. 
  Brit. 
  Diat. 
  p. 
  74, 
  Pl. 
  XII, 
  fig. 
  7. 
  

   Karlshamn, 
  Kalmar, 
  Gotland 
  (Cl. 
  & 
  Moll. 
  Diat. 
  N:o 
  86). 
  

   Only 
  in 
  almost 
  fresh 
  water. 
  

  

  N. 
  subdivisa 
  Grun. 
  

  

  In 
  the 
  Baltic 
  (Grun. 
  Aret. 
  Diat. 
  p. 
  29). 
  

  

  N. 
  palpehralis 
  Bréb. 
  

   VH. 
  D. 
  B. 
  Pl. 
  XI, 
  fig. 
  8. 
  

   Very 
  rare. 
  Ystad. 
  

  

  N. 
  elegans 
  Sm. 
  

  

  Sm. 
  Syn. 
  Pl. 
  XVI, 
  fig. 
  137. 
  

  

  Rathan 
  (Cl.). 
  

  

  N. 
  amphishcena 
  Bory. 
  

   VH. 
  D. 
  B. 
  Pl. 
  XI, 
  fig. 
  7. 
  

   Harbour 
  of 
  Visby. 
  

  

  Through 
  the 
  great 
  convexity 
  of 
  the 
  valve 
  of 
  this 
  and 
  

   the 
  two 
  snbsequent 
  species, 
  which 
  scarcely 
  ought 
  to 
  be 
  re- 
  

  

  