NO. 3] REMARKS ON NORTHERN LITHOTHAMNIA. 103 



Nordseef. (1874), p. 70! Kjellm. N. Ish. Algfl. (1883), p. 137? Batt. Cat. Brit. 

 Alg. (1902), p. 97, partim? 



Melobesia farinosa Kiitz. Spec. Alg. (1849), p. 696, partim, Tab. Phyc. XIX 

 (1869), p. 34, t. 95, cfr. Rosan. Rech. Melob. p. 62; Le Jol. Liste Alg. Cherb. 

 (1863), p. 150! Crn. Fl. Finist. (1867), p. 150, partim; Aresch. Obs. Phyc. Ill 

 (1875), p. 4! Reinke, Algenfl. westl. Ostsee (1889), p. 32! 



Lithophyllum pustulatum Le Jol. Liste Alg. Cherb. (1862), p. 151, partim! 



Hapalidium confervicola Magnus, Nordseef. (1874), p. 70. 



Melobesia Lejolisii Aresch. Obs. Phyc. Ill (1875), p. 3! Farl. Mar. Alg. New. 

 Engl. (1881), p. 180! Solms, Corall. Monogr. (1881), p. 1 1 ; Ardiss. Phyc. Medit. I 

 (1883), p. 445; Hauck, Meeresalg. (1885), p. 264, fig. 108; Weber-van Bosse, 

 Bijdr. Algenfl. Nederl. (1886), p. 3, fig. 1; Reinke, Algenfl. westl. Ostsee (1889), 

 p. 32; Debr. Cat. Alg. Maroc. etc. (1897), p. 72! Batt. Cat. Brit. Alg. (1902), 

 p. 96; De Toni, Syll. Alg. IV (1905), p. 1766. 



I take the typical form of the species as it is described 1. c, 

 at first forming small orbicular patches or irregularly flabellate ones, 

 which gradually become densely confluent. The cells are frequently 

 smaller, as well as shorter in proportion to the breadth, than in 

 M. farinosa. They are partly squarish, partly of a length IV4 or 

 up to about IV2 the breadth, being 8 — 15 p long and 7 — 10 fi 

 broad, occasionally a little larger. The cortical cells are very small, 

 but rather varying and sometimes approaching those of M. fari- 

 nosa, in which they are frequently a little larger and more regu- 

 larly semicircular. The last cell before a beginning dichotomy is 

 often hyaline here and there in the frond, and partly larger than 

 the adjacent cells. It sometimes greatly reminds of the heterocysts 

 in M. farinosa, and under slight magnifying it may easily be 

 confounded with such ones. In a vertical section the basal cells 

 resemble those in the said species, but they are frequently slightly 

 smaller, partly squarish, partly a little vertically, seldom horizontally, 

 elongated, 7 — 12 \i in diameter. In old specimens, and particularly 

 in such ones with crowded conceptacles, the greater part of the 

 frond is composed of 2 — 4 layers of cells, or new crusts are deve- 

 loped over the primary one. Therefore, the monostromatic part of 

 the frond is generally smaller in this species than in M. farinosa. 

 The conceptacles of sporangia and cystocarps are convex or sub- 

 hemispherical, frequently crowded, and almost confluent, 150 — 250 

 (300) fi in diameter. The conceptacles of antheridia are 75 — 100 ft 



