No. 3] REMARKS ON NORTHERN LITHOTHAMNIA. 73 



Melobesia corticiformis Kutz. Spec. Alg. (1849), p. 696; Tab. Phyc. XIX 

 {1869), p. 34, t. 94! Aresch. in J, Ag. Spec. Alg. 2 (1852), p. 518; Rosan. Melob. 

 (1866), p. 76, pi. I, fig. 14—16! Solms, Corall. Monogr. ( 1 88 1 ), p. 11; Born. Alg. 

 Schousb. (1892), p. 188. 



Melobesia verrucata Harv. Phyc. Brit. (1846—51), pi. 347 C? 



Melobesia rosea Rosan. Melob. (1866), p. 77! (Tab. II, fig. 1 — 2?) 



Hapalidium Hildenbrandtioides Crn., Alg. Finist. (1867), p. 149! 



Lithothamnion membranaceum Batt. Cat. Brit. Alg. (i902), p. 97? (cfr. M. 

 Lejolisii); De Toni, Syll. Alg. IV (1905), p. 1758. 



Lithothamnion corticiforme Fosl. List of Lithoth. (1898), p. 7; Debr. Cat. 

 Alg. Maroc etc. (1897), p. 72! Batt. Cat. Brit. Alg. (1902), p. 97! De Toni, Syll. 

 Alg. IV (1905), p. 1759. 



In List of Lithoth. 1. c, in Rev. Syst. Surv. p. 15 and in 

 Lithoth. Adr. Meer. etc. p. 20 I admitted L. membranaceum and 

 L. corticiforme as distinct species, following in this respect Mr. 

 Rosanoff and some recent authors. I had then not yet had the 

 opportunity of studying more closely the mutual relation of these 

 species, nor had I seen authentic specimens of any of them. But 

 now, by the kind liberality of Mr. O. Lignier, Professor at Caen, 

 and of Madame A. Weber — van Bosse, I have had the oppor- 

 tunity of examining the type-specimens oiM. membranacea Lamour. 

 and of M. corticiformis Kiitz. and found these two algas to be 

 identical. Also the form referred by Mr. Rosanoff to the latter 

 species belongs to L. membranaceum. The same is the case with 

 M. rosea Rosan. and most likely also with Hapalidium roseolum 

 Kutz. Be it said that L. membranaceum seems to have been 

 taken in a rather wide sense by Mr. Rosanoff. Thus I have 

 seen a specimen distributed by Mr. L e J o 1 i s, which according to 

 his label Mr. Rosanoff had partly referred to the said species 

 (M. membranacea), while as a matter of fact it only embraces 

 M. Lejolisii. Some recent writers also seem to have referred 

 specimens of M. Lejolisii to L. membranaceum, but I shall not 

 here enter upon that question. I will in this respect only observe, 

 as being of phytogeographical interest, that — as is mentioned below 

 under M. Lejolisii — I think it reasonable, at any rate for the 

 present, to assume that M. membranacea Kleen belongs to the 

 said species and not to the species in question. 



