Seii. GONGYLOSPERME^.. (125) Fam. CEKAMIACEyE. 



Plate CXI. 

 PTILOTA ELEGANS.— ii</fe. 



Gen. Char. — Frond linear, compressed or flat, disticbously pectinato-pinnate, coraposeil 

 of two strata, an axis composed of a simple articulated tube, finally covered by a 

 thick stratum of minute cells. Fructification of two kinds, on distinct plants : 

 1. Favellse, furnished with an involucre ; 2. Tetraspores, tripartite. Name from 

 -KTiAwTos, "pinnated." 



Ptilota sericeus. — Frond very flaccid, much and irregularly branched, 

 primary divisions having the axis covered with a coating of cells ; pinna; 

 and pinmilae consisting of the articulated axis ; favellse in pairs, with 

 or without involucral ramuli. 



Ptilota elegans. — Kiitz, Phyc. Gen. p. 378 ; /. G. Agardh, Sp. Gen. Alg. vol. ii. 

 p. 94. 



Ptilota 2:)lumosa, var. y tenuissima. — Ag. Sj^. Alg. vol. i. p. 386; Ag.Sysf. p. 195. 



Ptilota plumosa, capillaris. — Grev. Alg. Brit. p. 155; Hook. Br. Fl. vol. ii. 

 p. 307 ; Wyatt, Alg. Banm. No. 77 ; Ifarv. in Mack Fl. Hib. part S, 

 p. 204 ; Harv. Man. 1st edit. p. 84. 



Ptilota sericea. — Gmel. ; Harv. P. B. plate 191 ; Harv. Man. p. 160 ; Harv. Syn. 

 p. 129 ; Atlas, plate 49, fig. 222. 



Fucus sericeus. — Gm. Hist. Fuc. p. 149, t. 15, f. 3. 



¥vcvs Ptiloius. — Gicmi. Fl. Norv, vol. ii. p. 135, t. 2, f. 15; Esper, Ic. p. 96, 

 t. 46. 



Fucus pectinatus. — Gunn. Fl. Norv. vol. ii. p. 122, t. 2, f. 8 ; Esper, Ic. p. 97, 

 t. 47. 



Plocamium elegans. — Bory, see. Kiltz. 



Hab. — On the faces of perpendicular rocks between tide-marks; sometimes on Fuci. 

 Perennial. Summer and autumn. Common on the British shores. 



Gkogr. Dist. — Atlantic shores of Europe ; east coast of North America. 



Description. — Root, a small conical disc. Frond linear, compressed, 

 tufted, three to eight inches long, one quarter of a line in breadth, 

 much branched from near the base ; branches irregular, mostly alternate, 

 erecto-patent, two to four times pinnated ; jDinnae, and especially the 

 pinnulfe, very patent and filiform, all very iiTcgular in length, except 

 the ultimate divisions, which are longest above or below the middle, 

 giving the ramulus an ovate or lanceolate outline, all the divisions 

 pectinato-pinnate and distichous, the older often more or less toraentose, 

 with short, simple ramuli. Structure consisting of a central, simple, 



