203 



L. investiens. 



Fig. 2. A young specimen fastened to L. tophiforme f. squarrosa. 

 „ 3. Part of a free peripherical portion of an older specimen 



seen from above. 

 „ 4. The same portion seen from below. 

 „ 5. An older specimen fastened to L. fruticulosum. 



L. evanescens. 



Fig. 6 — 7. Habit-figure of an American specimen (6) and a Nor- 

 wegian (7). 

 „ 8. Conceptacles of sporangia seen from above. 



L. scabriusculum. 

 Fig. 9. Habit-figure of the plant. 



L. orbiculatum. 



Fig. 10. Habit-figures of younger and older, sporangia-bearing 

 specimens fastened to a stone. 

 „ 11. Apart of the crust with t-wo conceptacles of sporangia. 



L. Stromfeltii f. macrospora. 



Fig. 12. Habit-figure of a specimen with not fully developed con- 

 ceptacles of sporangia and a couple of young con- 

 ceptacles of cystocarps. The nature of the sur face is 

 not quite correctly reproduced by the lithographer. 



Pl. 23. 



Fossil Lithothamnia. 



Fig. 1—15. Specimens from Bodo (1 — 9) and from Garten at the 

 mouth of the Trondhj em Fjord (10—15), probably 

 at least partly referrible to L. fruticulosum. 



