20 



differing from specimens typically developed. Selfloosening or — I presume - - more usually 

 broken branches often seem to continue growing. 



form ubiaua constitutes roundish nodules which also seem to have been freely 

 developed ai the bottom. It is generally 2 cm. in diameter and is distinguished by rather 

 rivet, subfastigiate and straight branches, which, however, are partly rather crowded and knotty, 

 partly - and more frequently somewhat spreading. The branches are, as a rule, longer 



than in the form tualensis and 1 — 2 mm. thick, partly tapering, partly — but more rarely — 

 vvith somewhat thickened ends (PI. II, tïg\ iS — 24). Otherwise this form runs into the following 

 one, and there is no distinct line between them. 



The form brachiata is distinguished by spreading branches, more or less curved, sometimes 

 rather elongated, of about the same diameter as in the form ubia?ia. There are partly delicate 

 and sparingly branched specimens of this form. At any rate some of these specimens no doubt 

 have risen from broken branches, either of young specimens, or of the last order of older 

 specimens, continuing their growth. Thus there are such delicate specimens where one or more 

 surfaces of fracture are covered with new-formed tissue. 



The form of the species apparently most divergent is f. minutula. It is 0,5 — 1 cm. in 

 diameter, partly very sparingly branched with spreading and frequently short branches, partly 

 and oftener the branches are rather crowded, and sometimes it assumes an almost subfastieiate 



o 



shape. The branches are either terete and slightly attenuating, or cylindrical, or now and then 

 slightlv thickened towards the rounded ends, about 1 mm. thick. There is a rather ereat 

 number of specimens of this form from two stations, and they are of obvious conformity. 

 Cp. pi. II, hg. 39 — 50 from stat. 109, and hg. 51 — 62 from stat. 2S2. As I mentioned in 

 treating of L. fruticulosum, the form was sparingly mixed with specimens which seem to belong 

 to f. clavulata of the latter species or to be closely connected with f. soluta, and which are 

 on the whole hardly distinguishable. The other specimens, however, come nearest to L. australe 

 in the sense here taken, though they are also mixed up with fragments or small specimens 

 which may behing to another form not to be distinguished with certainty. There are several 

 specimens showing a surface of fracture more or less distinct and covered with new-formed 

 tissue. I take, however, f. minutula in the sense indicated by the specimens pictured. The 

 form approaches partly to L. australe f. tualensis, partly to f. brachiata, and it might be 

 supposed to have risen from both these forms and be considered as stunted specimens now of 

 one, now of the other. But this is not probable. It is perhaps more likely representing an 

 independent species, though all the specimens being sterile, it cannot for the time be settled. 

 A sure definition of this form (as well as of the others) will only be realised by a number of 

 fertile specimens or by investigations on the spot whether, for instance, the form constitutes 

 small and in the main independent banks, as the northern species Lithothamnion norvegicum 

 almost always sterile, which it somehow recalls, or if it only occurs together with other forms 

 of the species. 



What I remarked in treating of L. fruticulosum as to foreign bodies causing an irregular 

 development, also refers to the forms ranked with the species in question, though certainly to 

 a less extent. There are numerous specimens, particularly of the three forms first mentioned, 



