CEBAMIAC] L40 



mbbipinnate above ; the pinna or pinnules subhorizontal 

 or divaricate, the lowest Longest; articulations twic 

 thrice as Long as broad; tetraspores Qumerous, sessile on 

 the pinnules; favellse terminal; binate, Ag. 8p. Alg. v. 2. 

 p. ITU. (Atlas, PL L\ III. Kg. 266.) 

 Callithamnion Lanosum, ffarv. ('. Bpinosum, Harv, Phlebo- 

 thamnion Bookeri, Ktz. P. Bpinosum, Ktz. Ceramium 

 Bookeri, Ag, Oonfervs Bookeri, Dillto. 

 Hal. ()n various Algee, between tide-marks; also on rocks near 

 Low water-mark, and a1 a greater depth. Annual. Bummer. 

 A. common bui very variable species, and yei not diffi- 

 cult to understand when a few Leading features are kepi in 

 view. J is mosi striking characters are the opaque stem and 

 branches, the short articulations, and the very patent or 

 divaricated ramuli, frequently pinnulated above. It verges 

 on the one hand to ('. roseum, and on the other to C. 

 ri and to C. poly sp&r mum, luit is readily recognized 

 from each of these by some one of its characters. C. 

 Hookeri is named in honour of Sir W. J. Hooker, by 

 whom it was first discovered. 



261. roseum {The rosy Callithamnion) ; stems much and 

 Loosely branched; secondary branches Long, fiexuous, sub- 

 distichously plumulate j plumules lax, with a roundish out- 

 line, crowded towards the tops of the branches, Bimply 

 pinnate ; pinnsa Long, spreading, curved ; art Lculations of the 

 stem and branches four and five times as 1 « > 1 1 i_r as broad, 

 more or less filled with veins ; thoseofthe pinna twice or 

 thrice as Long as broad; tetraspores elliptical, four or live on 

 each pinna, from the Lower joints; favellse tufted, Lyngb. 

 Hyd. Van. p. 126. /. 29 (?). (Atlas, PL LV1. Pig. 260.) 

 Phlebothamnium roseum, Ktz. Ceramium roseum, Roth. Con- 

 ferva rosea, 12. Bot. 

 Jldb. On rocks and the larger Fuci, near low-water mark; fre- 

 quentlj in estuaries, or muddy places. Annual. Summer. 

 Not uncommon. 

 Callithamnion roseum is one oftlie Longest-described of 

 the genus, and oughl therefore, one would think, to be the 

 best-known. But, as with many old species, several plants 

 which are now distinguished, were formerly confounded 

 under this name, and thus it becomes a doubtful matter to 

 which of the modern species the original synonym roseum 

 attaches. As far however as the British Flora is con- 

 cerned, ^nv notions of ( } al. rosi vum are tolerably definite. 

 2(32. byssoideum [Thi byssus-like Callithamnion) \ Btems ex- 



