120 BYNOP8I8 OF BRITISH ^BA WEEDS. 



a geographical distribution, is almost a 



te. 



LWI. POLYIDES. 



206. rotundus {The round Polyides) ; root an expanded 

 frond cylindrical, dichotomous, cartilaginous, solid, the axis 

 consisting of denselj parked, Longitudinal, interlacing and 

 anastomosing filaments; the periphery of coloured, hori- 

 zontal, dichotomous filaments, whose Lower half is compos* d 

 of large, elliptical cells ; their upper of much smaller, sub- 

 moniliform cellules ; fructification of two kinds, on distinct 

 individuals; 1, oblong, irregularly formed, external warts, 

 composed of dichotomous filaments, through which arc scat- 

 tered elliptical la velke, having a broad pellucid limbus 

 cruciate tetraspores, immersed at intervals among the fila- 

 ments of the periphery, Qrev. A Ig. Brit. p. 70. t. 11. (Atlas, 

 PL XLYI. Fig. 212.) 



Folyides lumbricalis, Ag. Spongiocarpus rotundus, Grev. Fur- 

 cellaria rotunda, Lyngb. F. lumbricalis, Ktz. Chordaria 

 rotunda, Hook. Gigartina rotunda, Lamour. Fucus ro- 

 tundus, 0'/n. F. radiatus, Good and Woodw. F. caprinus, 

 Gunn. F. fastigiatus, Esper. 

 Hah. Frequent on the shores of England and Ireland. On rocks 

 in pools, within the tide-range. Perennial. Winter. 

 The genus Polyides is remarkable for its singular fruc- 

 tification, which strikingly differs both in appearance and 

 structure from that of any other of the Rhodospermeai. 

 In appearance the conceptacular fruit most nearly resem- 

 bles what are called nem at hecia, but the distinct and isolated 

 favellse which it contains are very different from the con- 

 tents of those imperfectly organized excrescences. Here, 

 in v hat look like irregular warts, we have most perfectly 

 formed and symmetrically arranged spores. 



LXVII. FURCELLARIA. 



207. fastigiata (The pointed Furcellaria) ; root branching ; 

 frond cylindrical, dichotomous, cartilaginous, solid ; the 

 axis consisting of densely packed, longitudinal, interlacing 

 and anastomosing filaments ; the periphery of coloured, 

 horizontal, dichotomous filaments, issuing from those of the 

 axis, whose lower half is composed of large, elliptical c 

 then' apices of much smaller cylindrical cellules ; fructifica- 

 tion "terminal, elongated, pod-like receptacles, containing 

 a stratum of dark, oblong, pear-shaped spores in the 

 eumference," Lamour. jEss.p.26. (Atlas, XLV. Fig. 2US.) 



