EXPLANATION OF PLATES. 
Plate III. 
All the figures are microphotographs after microtome-sections taken by Mr. A. Hessereo. 
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(6) 
Lithothamnion leve Strömf. Tetraspore (dispore), showing the nucleus with nucleolus 
(fallen out) and the structure of the protoplasm. (Specimen from Aalsgaarde). About 225:1. 
Lithothamnion Lenormandi (Aresch.) Foslie. Vertical section of antheridial conceptacle. 
(Specimen from TE”). About 200:1. 
Lithothamnion Lenormandi (Aresch.) Foslie. Vertical section of conceptacle of cystocarp. 
(Specimen from XQ). About 200:1. 
Lithothamnion glaciale Kjellm. f. Granii Fosl. Section of crustaceous frond with con- 
ceptacles of sporangia. ‘Specimen from Læsø Rende). About 180:1. 
Lithothamnion polymorphum (L.) Aresch. Vertical section of female conceptacle showing 
procarps. (Specimen from Store Middelgrund, May). 
Lithothamnion polymorphum (L.) Aresch. Vertical section of emptied conceptacles of 
sporangia with covering tissue. (Specimen from reef near Korsør). 
Plate IY. 
All figures from photopraphs in natural size. 
Lithothamnion glaciale Kjellm. f. Granii Fosl. 1 and 2 attached to stones, 3 free, 4 
similar one being on the point of dividing. (Specimens from IH, 3375). 
Corallina officinalis L., f. robusta Kjellm. (Specimen from YU, Hanstholm. 7286). In fig. 
5 the branchlets are partly verticillate. 
Corallina officinalis L., slender, slightly branched form with some stoloniform branches 
growing out in a transversal direction. (Specimen from UC, north of Leso, 5625). 
Corallina officinalis L. f. robusta Kjellm. With lateral conceptacles. (Specimen from 
MZ, 4058). 
