﻿14 
  JUHLIN-DANNFELT, 
  ON 
  THE 
  DIATOMS 
  OF 
  THE 
  BALTIC 
  SEA. 
  

  

  List 
  of 
  tlie 
  Baltic 
  Diatoms. 
  

  

  Ordo 
  I. 
  Placochromaticae. 
  

   Fam. 
  Oocconeidese. 
  

  

  Cocconeis 
  Ehb. 
  

  

  C. 
  Scutelluni 
  Ehb. 
  

  

  Exceedingly 
  common 
  in 
  the 
  southern 
  part 
  of 
  tlie 
  Baltic, 
  

   rather 
  common 
  on 
  the 
  coast 
  of 
  Roslagen, 
  scarcely 
  occurring 
  

   in 
  the 
  Gulf 
  of 
  Bothnia 
  and 
  in 
  the 
  Finnish 
  bay. 
  Very 
  seldom 
  • 
  

   found 
  in 
  bays 
  with 
  almost 
  freshwater: 
  Norrtelje. 
  

  

  v. 
  stauroneiformis 
  Sm. 
  

  

  Sm. 
  Syn. 
  Vol. 
  I, 
  p. 
  22, 
  Pl. 
  III, 
  fig. 
  34 
  a. 
  

  

  With 
  the 
  maiu 
  species, 
  not 
  common. 
  

  

  C. 
  Pediculus 
  Ehb. 
  

  

  V. 
  H. 
  D. 
  B. 
  Pl. 
  XXX, 
  figg. 
  28—30. 
  

  

  Very 
  seldom 
  in 
  the 
  southern 
  part 
  of 
  the 
  Baltic: 
  Sölves- 
  

   borg, 
  Gotland: 
  Ostergarn 
  (Cleve); 
  less 
  rare 
  in 
  the 
  Gulf 
  of 
  

   Bothnia: 
  Eathau 
  (Cleve), 
  Haparanda 
  (Cleye), 
  Ångermanland: 
  

   Näske 
  (Cleve). 
  

  

  C. 
  Placentula 
  Ehb. 
  

  

  V. 
  H. 
  D. 
  B. 
  Pl. 
  XXX, 
  figg. 
  '2Q, 
  27. 
  

  

  Common 
  in 
  all 
  parts 
  of 
  the 
  Baltic. 
  

  

  Besides 
  the 
  typical 
  form 
  that 
  is 
  also 
  common 
  in 
  fresh 
  

   water, 
  another 
  form 
  occurs 
  very 
  commonly 
  in 
  the 
  Baltic. 
  

   This 
  form 
  I 
  name 
  

  

  var. 
  haltica 
  no 
  v. 
  var. 
  

  

  Valve 
  larger 
  and 
  more 
  rounded 
  than 
  in 
  the 
  main 
  species, 
  

   striae 
  distinct, 
  about 
  15 
  in 
  0,01 
  mm., 
  punctate. 
  The 
  puncta 
  

   are 
  dense 
  on 
  the 
  inferior 
  valve, 
  on 
  the 
  upper 
  valve 
  they 
  

   are 
  more 
  distant, 
  forming 
  5 
  — 
  7 
  wavy, 
  longitudinal 
  rows. 
  The 
  

   frustule 
  is 
  plane 
  or 
  arched. 
  Length 
  0,035 
  — 
  0,045 
  mm., 
  breadth 
  

   of 
  the 
  valve 
  0,025 
  — 
  0,03 
  mm. 
  Plate 
  I, 
  figs 
  1 
  a 
  — 
  c. 
  

  

  Very 
  common 
  in 
  the 
  southern 
  part 
  of 
  the 
  Baltic, 
  more 
  

   scarce 
  in 
  the 
  Gulf 
  of 
  Bothnia. 
  

  

  ScHUMANN 
  ^j, 
  in 
  his 
  list 
  of 
  Prussian 
  Diatomaceae, 
  enume- 
  

   rates 
  the 
  following 
  species 
  as 
  occurring 
  in 
  the 
  Baltic: 
  

  

  ') 
  Preuss. 
  Diat. 
  1S67. 
  p. 
  U. 
  

  

  