48 LEATHESIA. 



branches lonj?, simple or forked, furnished with numerous alternate or se- 

 cuiid, spreading, flexuous raniuli. Frond to the naked eye appearing 

 villous, owing to the filamenls composing the periphery being very much 

 protruded beyond the gelatine, and accompanied also by colourless fibres, 

 similar to those of M. Griffithsiana. I have examined the M. (jracilis of 

 Carmicliael, and do not consider it specifically distinct from the present ; 

 and though I have not seen specimens of Mr. Berkeley's M. affinis, yet, 

 judging from the figure and description given in the ' Gleanings,' I ven- 

 ture to refer it to the young of this species. 



III. Leathesia. Gray. [Plate 10, C] 



Frond globose or lobed, carnoso-cavtilaginous, composed 

 of jointed, colourless, dichotomous filaments, issuing fi'om a 

 central point ; their apices (which constitute the fleshy coat- 

 ing of the frond) coloured and tufted. Fructification : oval 

 spores attached to the coloured tips of the filament. — Name, 

 in honour of the Rev. G. JR. Leaihes, a well-known British 

 naturalist. 



1. L. tuberiformis, Sm. ; fronds olivaceous, tuberous, when 



young filled with cottony fibres, at length hollow. Coryne- 



phora marina, Ag. ; Hook. Br. Fl. ii. p. 390 ; IVi/att, Alg. 



Danni. No. 149. Rivularia tuberiformis, Sm., E. Bot. t. 



1956. 



Between tide-marks, on rocks, corallines and Algge, abundantly. Annual. 

 Summer. — Fronds fleshy, forming many hollow lobed or distorted tubers, 

 and spreading over a large surface, olive-brown. " In young plants the 

 central cavity is traversed by a system of very wide, inflated, jointed, hya- 

 line tubes, branching dichotomously, while they radiate in all directions to 

 the surface, where each branch terminates in a tuft of short, club-shaped, 

 moniliform, coloured ramuli ; among these last, which by their lateral co- 

 hesion form the whole substance of the plant, the sporidia are found nestling. 

 They are obovate, smooth, and mostly solitary." — Carm. MSS. 



2. L. Berkeleyi, Grev. ; fronds dark brown, depressed, 



fleshy, solid ; filaments densely packed. Harv. Phyc. Brit. 



t. clxxvi. Chcstophora Berkeleyi, Grev. in Berk. Gl. t. \, 



f. 2 ; Harv. in Hook. I. c. p. 390 ; Wyatt, Alg. Damn. No. 



'231. 



On submarine rocks, between tide-marks. Annual. Summer. Soutli 

 of England and West of Ireland. — Fronds gregarious, 1 — 2 inches in di- 

 ameter, \ — \ inch thick, convex, but depressed, soft and fleshy. Filaments 

 very densely packed. Spores pear-shaped, produced in autumn. 



