334 KJELLMAN, THE ALGiE OF THE ARCTIC SEA. 



Part of an older specimen in transverse section. Vi- 

 Branch with conceptacles of sporangia, seen from above. Vi- 

 Part of thin transverse section of a branch. *%. 

 Part of median thin section of a branch. *"/!• 



Part of one of the outer concentric layers of a thin transverse section. 

 Part of the central layer in a thin transverse section. *"%. 

 Part of layer of tissue in a thin median section, "'/i. 

 Part of superficial, tangential thin section. *"%. 



Part of the roof a conceptacle of sporangia, delivered from lime. *'"'/i. 

 -14. Sporangia, ""/j. 



PLATE 4. 

 Lithothaumion intermediuni. 



Fig. 1. Full-grown specimen. Vi- 



» 2. Half of an older specimen, seen from the cleaving-surface. Vi- 



" 3. Branch with conceptacles of sporangia. -,\. 



» 4. Part of thin transverse section of a branch. ^*/j. 



» 5. Part of thin median section of a branch, ^'/j. 



» 6. Part of one of the outer concentric layers of a thin transverse section, ^""/i. 



» 7. Part of the central layer of a thin transverse section. *''''/i. 



» 8. Part of layer of tissue in a thin median section. '""'/|. 



y> 9. Part of superficial, tangential thin section. *'"'/j. 



1) 10. Sporangium. *"%. 



PLATE 5. 

 Lithothamnion alcicome. Fig. 1—8. 



Fig. 1. Older, fully developed specimen. Vi- 



» 2. Branch with conceptacles of sporocarps and of sporangia, ^/j. 



u 3. Part of thin median section of a branch. *%. 



» 4. Part of thin transverse section of a branch. *%. 



» 5. Part of one of the outer concentric layers of a thin transverse section. *""/,. 



» /}. Part of central layer of thin transverse section. *''*'/j. 



» 7. Part of layer of tissue in a thin median section. *"%. 



» 8. Sporangium. *"%• 



Lithothamnion norvegicum. Fig. 9—10. 



Fig. 9. Specimen from the north-west coast of Norway. Vi- 

 » 10. Specimen from the south-west coast of Norway, '/j. 



Lithothamnion foecundum. Fig. 11—19. 



Fig. 11. Part of specimen incrusting a stone. Vi- 

 » 12. Part of the crustaceous frond bearing conceptacles of sporangia, seen from above, ^j. 



