334 KJELLMAN, THE ALG OF THE ARCTIC SEA. 
Fig. 3. Part of an older specimen in transverse section. 1/,. 
» 4, Branch with conceptacles of sporangia, seen from above. ee 
» &, Part of thin transverse section of a branch. 4°/,. 
» 6. Part of median thin section of a branch. 4°/,. 
» 7. Part of one of the outer concentric layers of a thin transverse section. 4/,. 
» §. Part of the central layer in a thin transverse section. 4/,. 
» 9, Part of layer of tissue in a thin median section. 49/,. 
» 10. Part of superficial, tangential thin section. 4°/,. 
» L1. Part of the roof a conceptacle of sporangia, delivered from lime. 400 Fa 
» 12—14. Sporangia. 1°°/,. 
PLATE 4. 
Lithothamnion intermedium. 
Fig. 1. Full-grown specimen. 1/). 
» 2. Half of an older specimen, seen from the cleaving-surface. 1/,. 
» #%. Branch with conceptacles of sporangia. ?/;. 
» 4, Part of thin transverse section of a branch. 4°/, 
» 9, Part of thin median section of a branch. 4°/). 
» 6. Part of one of the outer concentric layers of a thin transverse section. 49/,. 
» 7, Part of the central layer of a thin transverse section. 4%/,. 
» &. Part of layer of tissue in a thin median section. 4°°/,. 
» 9. Part of superficial, tangential thin section. 49/,. 
» 10. Sporangium. 4°°/,. 
PLATE 5. 
Lithothamnion alcicorne. fig. 1—8. 
Fig. 1. Older, fully developed specimen. '/,. 
» 2. Branch with conceptacles of sporocarps and of sporangia. 2/,. 
» &. Part of thin median section of a branch. 4°/,. 
» 4, Part of thin transverse section of a branch. 4%/;. 
» 9%, Part of one of the outer concentric layers of a thin transverse section. 4/,. 
» 6. Part of central layer of thin transverse section. 1°°/,. 
» 7. Part of layer of tissue in a thin median section. 49°/,. 
» 6, Sporangium. 4°°/,. 
Lithothamnion norvegicum. Ig. 9—10. 
Fig. 9. Specimen from the north-west coast of Norway. 1). 
» 10. Specimen from the south-west coast of Norway. '/,. 
Lithothamnion foecundum. fg. 11—/9. 
Fig. 11. Part of specimen incrusting a stone. 1/,. 
» 12. Part of the crustaceous frond bearing conceptacles of sporangia, seen from above. 
