Sek. GONGYLOSPEEMEiE. (103) Fam. CERAMIACEJ;. 



Plate CXXI. 

 CALLITHAMNION TETEAGONUM.— .4^. 



Gen. Char. — Fronds filiform and articulated, sometimes at length in the older parts 

 cellular and partially opaque, single-tubed ; divisions mostly pinnate, dissepiments 

 hyaline. Fructification of two kinds, on distinct plants : 1. Favellse, mostly 

 lateral on the branches, and filled with minute spores ; 2. Tetraspores, external, 

 tripartite or cruciate. Name from KctAbs, "beautiful," and fia^ros, "a shrub." 



Callithamnion tetragonum. — Frond with a rather stout perciu-reut 

 main stem, tapering, opaque at the base, three or fom* times somewhat 

 quadrifariously branched, those branches near the base longest ; penul- 

 timate plumules long, slender, with a linear outline, and set with 

 alternate, short, closely pinnate or bipinnate plumules, the pinnulae 

 erect, incui'ved, thickened upwards, and shortly acmninate ; articulations 

 two to tlu-ee times as long as broad, those of the pinmdes once or once 

 and a-half as long as broad ; tetraspores minute, produced at the apices 

 of the pinnula) ; favellse on abbreviated pinnulae. 



Callithamnion tetragonum. — Ag. Bp. Alg. vol. ii. p. 176; Wyait, Alg. Damn. 

 No. 90 ; /. Ag. Alg. Medit. p. 74 ; Endl. 3rd Suppl. p. 34 ; Uarv. 

 in Hook. Br. Fl. vol. ii. p. 343 ; Harv. in Made. Fl. Bib. part 3, 

 p. 215 ; Harv. P. B. plate 136 ; Harv. Man. p. 175 ; Harv. Syn. 

 p. 147; Atlas, plate 57, fig. 264; Harv. N. B. A. part 2, p. 230; 

 /. G. Agardh, »S/j. Gen. Alg. vol. ii, p. 53. 



Ceramium tetragonum. — Ag. Syst. p. 137. 



Conferva tetragona. — With. Br. PL vol. v. p. 405 ; D'dlv). Conf. t. 65; E. Bot. 

 t. 1690. 



Hab. — Parasitical on the Laminarice. Annual. Summer. Common. Shores of 

 England and Ireland. Rare in Scotland. Arran and Ayrshire coasts {Fev. D. 

 Landsborough). 



Geogr. Dist. — Atlantic shores of Europe ; Baltic and Mediterranean Seas. 



Description. — Root, a flattened, conical, spreading disc. Fronds with 

 the main stem rather stout and percurrent, at length more or less per- 

 vaded by opaque veins or jointed filaments, and in age becoming more or 

 less covered with short branching pile, and beset from near the base 

 with scattered, rather patent branches of very irregular length, from 

 that of the short pile which covers the stem, to that of two or two 

 and a-half inches ; these are again once or twice branched in a similar 

 manner, the ultimate branchlets regularly set with very short and rather 



