44 



Tromsø Museums Aarshefter. 14 1891. 



enlarged towards the tip, with the ends mostly obtuse or 

 not seldom rounded, 1—2 mm. in diameter, and sometimes 

 carrying small warWike processes. In adjacent crusts stum" 

 bling each other, the edges get compressed and raise them- 

 selves in their further growth against each other, forming 

 elevated, rough and wavy ridges, or sometimes the one edge 

 gripes over the other. The colour is 



dark 



rosy, getting 



/ 



much paler a short time after the plant has been removed 

 from the water. 



In a young state the species much resembles a youn- 

 ger Lifhophyllum Lenormandi in habit. However, the pro- 

 cesses appear very soon. It often lives jointly with L. Le 

 normandi f. læve and grows over it. I have seen stones on 

 which firstly Lithophyllum has been growing, and afterwards 

 Lithothamnion colliculosum has germinated on the same sto- 

 ne and in its further growth sometimes quite covered the 

 former, sometimes leaving small parts of sporangiferous in- 

 dividuals uncovered, 



The basal layer of the crust is rather feebly developed. 

 In a fragment of a crust about 1.5 mm. thick it takes up 

 about 200 \x. The limit between the lower layers of tissue 

 especiallyis difficult to detect on a section The innercells 

 of these layers are squarish or rectangular with rounded cor- 

 ners and rather thin walls. The processes on the other hand 

 show in a longitudinal section distinct and mostly regular 

 cup shaped layers, with the inner cells in general more elon- 

 gated than those in a corresponding section of the crust 

 squarish or rectangular with rounded corners, 8—12 (j. high 

 and 5—8 [x broad. 



The species was provided with conceptacles of sporo- 

 carps in the beginning of September. They were pretty com- 

 mon and scattered over the crust as well as the processes 

 without any order, conical, most often acute, 300—500 [xin 

 diameter at the base and when mature upwards traversed 





