M. Foslie, Contribution II. 



39 



mens with the originally included object have a mueh vary- 

 ing form, though most often subspherical or hemispherical. 

 By and by they open themselves on the lower side, and the 

 object falls out. Old specimens are arch-shaped with a ge- 

 nerally subcircular circnmference, until 40 cm, in diameter 1 

 by a thickness of 1 — 2 cm., the upper side convex or hemis- 

 pherical, the lower side concave. Pl. 2, the upper figur e. 

 The primary crust of such specimens has most often disap- 

 peared, and the lower side of the frond is much rubbed so 

 that the interwalls between the branchsystems are visible 

 from this side. Pl. 2, the lower figure. Sometimes the na- 

 med side is still furnished with a thin crust, and now and 

 then new and short branches issue from it. In specimens 

 newly opened and the included object tallen out, the invo- 

 lucrated edges of the frond sometimes gro w inwards and by 

 and by replenish the opening, forming a slightly concave 

 base. The plant has a light rosy colour. 



A longitudinal section of a branch shows distinct and 

 regular cup-shaped layers of tissue. The inner cells of these 

 layers are squarish or rectangular with rounded corners, 9 

 11 p. high and 5 — 8 p. thick. I have examined several spe- 

 cimens without finding overgrown conceptacles of sporangia. 

 I therefore suppose that these organs ahvays are superficial. 

 The species was steril when collected in the middle of Sep- 

 tember, but below the tip of the branches were found a num- 

 ber of mostly densely crowded small and shallow holes, in- 

 visible to the naked eye, which I suppose to be the emp- 

 tied superficial conceptacles of sporangia with the roof fal- 

 len off. 



Amongst the northern Lithothamma, this species stands 

 nearest to L. TJngeri. Old and typically developed speci- 

 mens are distinguished at a glance, quite different from the 



*. From the boat I saw still larger specimens lying loose on the bot- 

 tom, but I did not jet hold of them. 



