Ser. CHLOiiosrERMEiE. Earn. Valoniacea. 



Plate V. 



APJOHNIA L^TEVIRENS. Han. 



Gen. Char. Frond stipitate, dendroid. Stipes rooting, unicellular and 

 monosiphonous, transversely rugulose, thinly coated with calcareous 

 matter, at maturity crowned with a pencil of branches. Branches 

 confervoid, umbellate, polychotomous, fastigiate, free, articulated ; 

 articulations clavate, annulated at base, and filled with bright green 

 watery endochrome. — Apjohnia {Harv.), in honour of Professor Ap- 

 john of Dublin, and of Mrs. Apjohn, a zealous algologist. 



Frons stipitata, dendroides. Stipes radicatus, monosiphonius, clavatus, continuns, 

 annulatim constrictus et transversim rugulosus, epidermide tenni calcarea do- 

 naius, in (state majore ramis coronatus. Rami conferva idei, umbellati, poly- 

 chotomi, fastigiati, liberi, articulati ; articulis clavatis, omnibus basi nodoso- 

 annulatis, succo aqiioso viridissimo repletis. 



Apjohnia Icetevirens, Harv. 



Apjohnia ketevirens, Harv. in Tayl. An. Nat. Hist. ser. 2. v. 15. p. 335. 

 Harv. Alg. Austr. Exsic. n. 566. 



Hab. On the steep sides of rock-pools, near low-water mark. Philip Is- 

 land, Western Port, and at Port Pairy, Victoria, W. H. H. Port 

 Lincoln, South Australia, Mr. Wilhelmi. 



Geogr. Distr. As above. 



Descr. Fronds rising from a mass of very tough and rigid, branching, unicellular 

 fibres, densely tufted, 3-6 inches high, stipitate and tree-like. Stipes from 

 1-2 inches long, club-shaped, nearly two lines in diameter at the thickened 

 upper extremity, tapering gradually to the base, consisting of a single cell 

 filled with watery fluid. In the first stage of growth the whole frond consists 

 of this stipes, which is then of a bright green colour, quite obtuse or rounded 

 at the extremity, and scarcely at all coated with calcareous matter. As the 

 frond progresses toward maturity, a minute conical cell, which never increases 

 much in length, is formed at the apex of the stipes ; and round the base of 

 this cell a whorl of cylindrical, basally nodoso-constricted cells are gradually 

 developed. These latter increase in length, and as they grow, each emits 

 from its summit generally three similar cells ; and this process is repeated 

 several times, till there results a penicillate umbel of trichotomous, confer- 

 void, articulate branches. Every internode or articulation of the branches 

 is annularly constricted towards the base. At first the branches, like the 

 young stems, are membranous and glossy, but they afterwards become thinly 

 incrusted with carbonate of lime. The substance is firmly membranaceous, 

 and the plant very imperfectly adheres to paper in drying. The endochrome 

 is of a vivid green colour, but is thin and watery. 



At first sight the plant here figured may pass for a very ro- 



