CALLITHAMNION. 181 



nate ; articulations of the stem cylindrical, 3 or 4, of pinnae 

 2 or 3 times longer than broad ; tetraspores on the tips of 

 the pinnules. Harv. in Hook. Br. Fl. ii. p. 345 ; Wyatt, 

 Alg. Danm. No. 45. 



On mud-covered rocks near low-water mark. Pier, Torquay, Mrs. 

 Griffiths. Milford Haven, Mr. Ralfs. Falmouth, Miss Warren. Ply- 

 mouth, abundantly, Rev. W. S. Hore, &c. Filaments 1 4 inches high, 

 irregularly branched, exceedingly slender, distichous; main branches few, 

 unequally plumulate for their whole length; lower plumules short, vaguely 

 pinnate ; upper from half an inch to an inch long, narrow-ovate or lanceo- 

 late, acute, patent, bi-tripinnate ; outline of the principal branches broadly 

 ovate. Colour rose-red. Tetraspores minute, elliptical, on the tips of 

 shortened pinnulae. Favellce roundish, lobed, on the principal branches. 



23. C. thuyoideum, Sm. ; repeatedly branched in an alter- 

 nate manner, distichous ; branches set with alternate, lanceo- 

 late, narrow, bipinnate plumules ; articulations of the stem 

 2 6 times longer than broad ; capsules on the tips of the 

 pinnulae. Harv. in Hook. Br. Fl. ii. p. 346 ; Harv. Phyc. 

 Brit. t. cclxix. Cow/, thuyoides, E. Bot. t. 2205. Cal. tri- 

 pinnatwn, Harv. I. c. (not of Agardh) ; Wyatt, Alg. Danm. 

 No. 186. 



On rocks near low-water mark, rare. Yarmouth, Mr. Borrer. Ply- 

 mouth, Mr. Sconce. Pier, Torquay, Mrs. Griffiths. Wicklow. Porta- 

 ferry, Mr. W. Thompson. Roundstone, Mr. W. M'Calla. Frond 1 or 2 

 inches high, sub-simple below, alternately branched above, the branches 

 distichous, generally having two or more series of lesser branches, which 

 are also alternate ; the minor branches, and sometimes all the divisions of 

 the frond, set at every joint with alternate, patent, closely bipinnate plu- 

 mules, of a very narrow, linear-oblong figure. Articulations of the stem 

 very variable in length in different specimens ; in some twice, in others 

 six times as long as broad, more or less swollen at the joints. Tetraspores 

 on the tips of shortened pinnulae. Colour a fine rose-red. Substance soft 

 and flaccid. The first plumule of the branches or pinnule of the plumules 

 frequently rises from the axil, especially in a variety having shorter joints 

 to the stem than usual, which led me in Br. Fl. to regard this variety as 

 the Cal. tripinnatum of Agardh, a species, one of whose chief characters is 

 this axillary ramulus. Agardh's plant proves, however, on inspection of 

 authentic specimens, to be very different, and, having been recently disco- 

 vered in Britain, is above described. 



Section 4. CORYMBOSA. Stems articulated ; ramuli dicho- 

 tomous. (Sp. 2426.) 



24. C. corymbosum, Sm. ; capillary, flaccid, gelatinous; 

 secondary branches alternate, excessively dichotomous, sub- 

 flabellate, level-topped ; ramuli dichotomous, byssoid ; arti- 

 culations of the branches 8 10 times longer than broad ; 



