324 29. Callith. S.THALASSIOPHYTbE. Pl.ceU.aph. 
Sea-coast; September, October. 
Thallus tufted, 1 or 2 inches long; joints of the stem 4 
to 6 times as long as broad, of the twigs only as long. 
5. Callith. tetragonum. Four-sided pretty-weed . 
Thallus much-branched, red; twigs bundled, short, 
spreading horizontally attenuated at bottom, pointed at 
the tip ; joints ovate-cylindrical, twice as long as broad. 
Conferva (etragona, Withering Bot. 4, 405; Engl. But. 1690. 
Sea-shore, or parasitical on other sea-plants. 
Thallus tufted, 2 or 3 inches long; branches 4-sided, 
sides hollowed ; joints of the twigs about as long as broad ; 
thecae globular. 
6. Callithamnion tetricum. Dirty pretty-weed . 
Thallus several times pinnated, brown red, lurid ; seg- 
ments and lobes alternate ; points rather curved ; joints 
about 3 times as long as broad ; thecae single, slightly pe- 
dicelled. 
Conferva tetrica, Dillwyn Conf. 81 ; Engl. Bot. 1915. 
Sea-shore, on stones and marine plants. 
Stems many, tufted, 6 or 8 inches high, alternately* 
doubly pinnate ; twigs pinnate ; joints equal. 
7. Callithamnion Hookeri. Hooker s pretty-weed . 
Thallus very much branched; stem thick, not visibly 
jointed, pale reddish-brown; twigs crowded, short, ‘[pin- 
nate ; lobes alternate, jointed ; joints rather longerj’than 
broad. 
Conferva Hookeri, Dillw. Conf. 106. 
Sea-shore. 
8. Callithamnion floccosum. Flock pretty-weed 
Thallus branched, rose-colour ; branches alternately pin- 
nated ; segments opposite, pectinated, horizontally recurved; 
lobes pointing one wa y ; joints about [3 times Jas long as 
broad. 
Conferva Turneri, Engl. Bot. 1637. 
Conferva Plumula, Ellis Ph. Tr . 57, 425 j D iliac. Conf. 50. 
Conferva floccosa, Ft. Dan. 828. 
Ceramium floccosum, Roth Cat. 2, 185. 
Ceram iu rn Plumula, Agardh Syn, 62. 
Sea-sliore; May to July. 
Thecae sessile, globular, on the lobes. 
