. 



M. Foslie. Contribution IL 



37 



Lithothamnion boreale nob. 



L. fronde initio affixa (?), deraum libera in fundo jacente, subdi- 



chotome ramosa; ramis ex hypothallo lobato, subvalido egredientibuå, 

 subdiebotomis vel subsimplicibus, plerumque ei*ectiusculis usque 7 cm. 



altis, 1.5 cm. crassis, ramulis numerosis, brevibus, plerumque verrucæfor- 

 mibus præditis; conceptaculis sporangiferis nunquam innatis (?). Tab. 1. 



Sorae years ago I got a specimen of a Lithotham- 

 nion which was said to have been picked up from a depth 

 of about 20 fathoms at Gjesvær in the neighbourhood of the 

 North Cape. It seems to be most nearly related to L. gla- 

 ciale or L- calcareum, or perhaps to be an intermedia- 

 te form between these two species. However, as it is sepa- 

 rated form the former by rather easential characteristics and, 

 as I have not seen any specimen of the latter, a plant which, 



as described by Harvey and Johnson, is supposed to 



include different species, I am obliged to regard it as a dis- 



tinet species. , 



The specimen seems to have been attached at first, and 



afterwards it has detached itself and lain free on the bot- 

 tom. From a crustaoeous, pretty strongly developed hypo- 

 thallus with nnmerous processes or lobes arise a number of 

 subdichotomous or subsimple, erect and vigorous, more or 

 less remoted branches, attaining a hight of 7 cm. and a 

 thickness of 15 cm. These carry numerous simple, short 

 and wart-like or longer and branch-like irregularly issuing- 

 processes reaching a length of about 5 mm. The lowerside 

 of the hypotallus bears some raostly younger branches which 

 are generally short and not seldom decumbent so that the 

 hypothallus seems by and by to form a subcentral main axis. 

 The specimen has a yellowish white colour, but it had been 



■ 



bleached in the sun for some time when I got it. 



A longitudinal section of a branch shows pretty regu- 

 lar cup-shaped layers of tissue, but they are not sharply 

 marked and often almost impossible to detect. The inner 

 cella of these layers are sqnarish or rectangular with roun- 





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