No. 3] REMARKS ON NORTHERN LITHOTHAMNIA. 59 



15. Lithothamnion Oranii Fosl. 



Rev. Syst. Surv. Melob. (1900), p. 1 1 ; Lithothamnion flabellatum f. Granii 

 Fosl. Norw. Lithoth. (1895), p. 70, t. 17, fig. 1—7, t. 22, fig. 1 (excl. f. Rosen- 

 vingii); De Toni, Syll. Alg. IV (1905), p. 1731. 



f. typica. 



Descr. Lithoth. flabellatum f. Granii Fosl. Norw. Lithoth. 1. c. 



f. reducta Fosl. mscr. 



Frond 1 — 3 cm. in diameter, branches spreading or crowded, 

 shorter and often thinner than in the typical form. 



Syn: Lithothamnion Battersii Fosl. New or crit. Lithoth. (1895), p. 1? Batt. 

 Cat. Brit. Mar. Alg. (1902), p. 97? De Toni, Syll. Alg. IV (1905), p. 1733? 



In Norw. Lithoth. I described L. Oranii as a form of L. 

 -flabellatum Rosenv., whereas in Rev. Syst. Surv. Melob. I, with 

 some doubt, admitted the former as an independent species. Ho- 

 wever, I have formerly felt a doubt whether L. Granii should not 

 be regarded as a form of L. glaciale. I have above p. 10 sug- 

 gested that it might be looked upon as a relict form of the species 

 last .named, but on the other hand found this hypothesis less prob- 

 able. It is most likely to be regarded as an independent species, 

 partly resembling young and delicate forms of L. glaciale, partly 

 closely connected with L. tophiforme f. divergent. There are 

 several specimens particularly of the latter species — not only 

 young ones, but even rather old ones — which are quite like each 

 other in almost every respect, but that the specimens of one spe- 

 cies shows a somewhat greater tendency in one direction and the 

 other in a different one. Thus the branches in L. Granii are as 

 a rule thinner, shorter and provided with more numerous short 

 lateral branches than in L. tophiforme f. divergens. Besides, it 

 nearly always at first forms a thin crust developing branches 

 more or less crowded, whereas L. tophiforme is in general freely 

 developed at the bottom, and the conceptacles are mostly a little 

 smaller than in the latter. 



The form reducta is in fact only a stunted form of the spe- 

 cies, but it is frequently so peculiar and diverging that it ought 

 to be looked upon as a particular form. It is found attached to 

 small pebbles from which it is often detached so as to lie freely 



