No. 3] REMARKS ON NORTHERN LITHOTHAMNIA. 119 



Melobesia membranacea Kiitz. Phyc. gener. (1843), p. 385, t. 78 I; Spec. 

 Alg. (1849), p. 696; Tab. Phyc. XIX (1869), p. 33, t. 93! 



Pneophyllum fragile Kiitz. Phyc. gener. (1843), p. 385, Spec. Alg. (1849), 

 p. 695, Tab. Phyc. XIX (1869), p. 33, t. 93; De Toni, Syll. Alg. IV (1905), 

 p. 1712. 



Fhyllactidium confervicola Kiitz. Phyc. gener. (1843), p. 295. 



Melobesia grandiuscula Mont. Fl. Alg. (1846), p. 138, Syll. crypt. (1856), 

 no. 1526; De Toni, Syll. Alg. IV (4905), p. 1770? 



Hapalidium Phyllactidium Kiitz. Spec. Alg. (1849), p. 695! Tab. Phyc. XIX 

 (1869), p. 33, t. 92. 



Melobesia frondosa var. incrustans Pice. Erbar. Crittog. Ital. no. 177 (1177)! 



Hapalidium confervicola Aresch. in J. Ag. Spec. Alg. 2 (1852), p. 509; Ardiss. 

 Phyc. Med. I (1883), p. 449; De Toni et Levi, Phyc. Ital. no. 15! 



Melobesia confervicola Fosl. Rem. Melob. Herb. Crouan (1899), p. 7 ; De Toni, 

 Syll. Alg. IV (1905), p. 1766. 



Melobesia confinis Crn. Fl. Finist. (1867), p. 150, partim! 



Peyssonnelia involvens Kiitz. Tab. Phyc. XIX (1869), p. 31, t. 87! (Non 

 Zanard). 



Melobesia Cystosirae Hauck, Meeresalg. (1885), p. 265, partim! De Toni, 

 Syll. Alg. IV (1905), p. 1770. 



Melobesia Corallinse Solms, Corall. Monogr. (1881), p. 9, t. II, fig. 25, III, 

 fig. 21 — 24; Hauck, Meeresalg. (1885), p. 266; Born. Alg. Schousb. (1892), p. 188; 

 Debr. Cat. Alg. Maroc. etc. (1897), p. 72! De Toni, Syll. Alg. IV (1905), p. 1768. 



Lithophyllum Corallinae Heydr. Corall. insb. Melob. (1897), p. 47. 



In the List of Lithoth. 1. s. I stated Melobesia macrocarpa 

 Rosan. as a form of M. pustulata, whereas in Rev. Syst. Surv. 

 Melob. I admitted it as an independent species under Dermatoliii hon. 

 I then mentioned that I had not seen any authentic specimen. 

 Afterwards I have had the opportunity of examining such one. 

 Cp. Rem. Melob. Herb. Crn. p. 14. However, I am not able to 

 draw anything like a definite line between any of the forms stated 

 above, most of which have formerly been looked upon as inde- 

 pendent species. The shape an the thickness of the frond, the 

 shape and the size of the cells, the shape and the size of the 

 conceptacles are mutually much varying and numerous transitions 

 may be pointed out from one form to another. The essential 

 characteristic has been the parting of the sporangia. But even this 

 criterion does not prove constant. Thus the forms australis and 

 intermedia, stated above, are included in Melobesia pustulata in 



