a 
Ser. RHODOSPERMEA. Fam. Ceramiee. 
Piate CXXXVI. 
CALLITHAMNION TETRAGONUM, 4. 
Gun. Cuar. Frond rosy or brownish-red, filamentous; stem either opake 
and cellular, or translucent and jointed; branches jointed, one-tubed, 
mostly pinnate (rarely dichotomous or irregular); dissepiments hyaline. 
Fruit of two kinds, on distinct plants; 1, external ¢etraspores, scat- 
tered along the ultimate branchlets, or borne on little pedicels; 2, 
roundish or lobed, berry-like receptacles (favel/e) seated on the main 
branches, and containing numerous angular spores. CALLITHAMNION 
(Lyngb.),—from xadus, beautiful, and Oaprior, a little shrub. 
CALLITHAMNION ¢e¢vagonum; outline of the frond ovate; stem cartilagi- 
nous, sub-simple, setaceous, somewhat opake, vey, set with subqua- 
drifarious lateral branches, furnished sometimes with a second or third 
series; penultimate branches pellucidly jointed, slender, elongate, set 
with short, alternate, patent, level-topped plumules, the lowest of which 
are simply pinnate, the upper sub-bi-pinnate; ramuli incurved, nar- 
rowed at the base, suddenly acuminate, their articulations once and a 
half a long as broad, constricted at the joints; tetraspores exceedingly 
minute, oval, near the tips of the ramuli. 
CALLITHAMNION tetragonum, 4g. Sp. Alg. vol. ii. p.176. Harv. in Hook. 
Br. Fl. vol. ii. p. 343. Harv. in Mack. Fl. Hib. part 3. p.215. Harv. 
Man. p.108. Wyatt, Alg. Danm. no. 90. J. Ag. Alg. Medit. p. 74. 
Endl. 3rd Suppl. p. 34. ' 
CERAMIUM tetragonum, 4g. Syst. p. 137. 
ConFerva tetragona, With. vol. v. p. 405. Dillw. Conf. t. 65. #. Bot.t. 1690. 
Has. Parasitical on the larger Algee; commonly on the fronds of Lami- 
naria digitata. Annual. Summer. Shores of-England and Ireland. 
Guoer. Distr. Atlantic shores of Europe. Baltic and Mediterranean Seas. 
Deuscr. Root scutate. Fronds from two to five inches in length, with a broadly 
ovate general outline. Stems thicker than hog’s bristle, smooth, or clothed 
with short hair-like ramelli, jomted, but more or less opake from the veins 
which traverse the articulations, subsimple, furnished throughout with 
numerous lateral patent, alternate, subquadrifarious, simple branches, 
the lowermost of which are longest. These dvanches are similar to the 
main stem, and bear a second or third series of lesser branches, all of which 
are perfectly simple. The penultimate branches are about half an inch long, 
pellucidly jointed, and clothed with very short plumules, set alternately. 
Plumules not half a line in length, the lowermost sub-simple or pinnate, the 
upper gradually more compound. Ramuli curved, robust, thickest in the 
middle, suddenly acuminated at the point. Articulations of the stem and 
branches from two to three, or rarely four times as long as broad ; those of the 
ramuli pretty constantly once and a half as long as their breadth. etra- 
spores very minute, oval or oblong, sometimes transversely zoned, usually 
tripartite, borne near the tips of the ramuli, one or two on each ramulus. 
E 2 
