76 M. FOSLIE. [1905 



f. sublcevis Fosl. mscr. 



Lithothamnion polymorphism f. papillata Fosl. Norw. Lithoth. (1895), p. 87, 

 pi. 17, fig. 22-23. 



f. tuberculata Fosl. 



Norw. Lithoth. p. 86, pi. 17, fig. 17—19. 



f. valida Fosl. 



Norw. Lithoth. p. 86, pi. .17, fig. 2C— 21. 



Syn: Melobesia polymorpha Harv. Man. 2 (1849), p. 108, partim; non Phyc^ 

 Brit. pi. 345, nee. Ner. austr. p. 110. 



Spongites polymorpha Kiitz. Spec. Alg. (1849), p. 699, partim. 



Spongites Crustacea Kiitz. Phyc. gener. (1843), p. 386; Spec. Alg. (1849), 

 p. 689; Tab. Phyc. XIX, p. 34, t. 97! Aresch. in J. Ag. Spec. Alg. 2 (1859), 

 p. 519. 



Lithothamnion polymorphum Aresch. in J. Ag. Spec. Alg. 2 ( 1 852), p. 524, partim . 

 Alg. Scand. exsicc. no. 302! Obs. Phyc. Ill (1875), p. 5, partim! Le Jol. Liste 

 Alg. Cherb. (1863), p. 151, partim; Rosan. Rech. Melob. (1866), p. 99, partim; 

 Crn. Fl. Finist. (1867), p. 151, partim; Kleen, Nordl. Alg. (1874), p. 11, partim; 

 Kjellm. N. Ish. Algfi. (1883), p. 134, partim; Stromf. Algveg. Isl. (1886), p. 19; 

 Traill. Alg. Mar. Orkney (1890), p. 36; Fosl. Contrib. I (1900), p, 9, partim, Norw. 

 Lithoth. (1895), p. 87; Simm. Meeresalg. d. Faeroer (1897), p. 269; Jonss. Mar. 

 Alg. Icel. I (1901), p. 154! B5rg. Mar. Alg. Fteroes (1902), p. 400! Mar. Alg. 

 Shetl. (1903), p. 7. Non Hauck. Meeresalg. 



Lithothamnion purpureum Crn. Fl. Finist. (1867), p. 150! 



Eleutherospora polymorpha Heydr. Lithoth. Helgol. (1900), p. 65! 



Lithothamnion testaceum Heydr. 1. c. p. 77 ! (Non Fosl.) 



Phymatolithon polymorphum Fosl. Rev. Syst. Surv. Melob. (1900), .p. 9; Batt. 

 Cat. Brit. Alg. (1902), p. 98! Fosl. Lithoth. Adr. Meer. etc. (1904), p. 20, 35; 

 De Toni, Syll. Alg. IV (1905), p. 1724. 



As 1 already mentioned in Norw. Lithoth. 1. c, the forms of 

 this species admitted above are but feebly differentiated, and often 

 run into each other. There is, however, a considerable difference 

 between an almost even forma sublwvis and a coarse f. valida, 

 and the intermediate f. hiberculata is a rather characteristic form, 

 which frequently occurs in exposed places, partly sheltered by 

 other alga?. The species almost always grows on rocks (or in 

 rock-pools). Sometimes it partly covers the hapters of Laminaria 

 and Alaria, or the root of Fucus and, towards the southern limit 

 of its distribution, occasionally also other calcareous alga;. Along 

 the northern part of the coast of Norway it often grows in com- 



