Ser. GONGYLOSPEKMEiE. ( 121 ) Fam. CERA MIA OE.E. 



Plate CX. 

 PTILOTA PLUMOSA.— vi^. 



Gen. Char. — Frond linear, compressed or flat, distichously pectinato-pinnate, composed 

 of two strata, an axis comj)osed of a simple articulated tube, finally covered by a 

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

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

 TTTiAofTof, "pinnated." 



Ptilota jihunosa. — Fronds linear, compressed, inegularly branched ; 

 branches mostly tripinnate, phanse and pinnulae opposite ; favellse 

 stalked, involucrate, alternating with the pinnulee ; tetraspores stalked, 

 fringing the margins of the pinnules. 



Ptilota plumosa. — Ac/. Sp. Alg. vol. i. p, 358 (excl. var. /3) ; Ag. Syst. p. 195 ; 

 Lyngh. Hyd. Dan. p. 38, t. 9 ; Grev. Fl. Edin. p. 297 ; Spreng. Syst. 

 Veg. vol. iv. p. 344 ; HooJc. Fl. Scot, part 2, p. 106 ; Grev. Alg. Brit. 

 p. 155, t. 16 ; Hook. Br. Fl. vol. ii. p. 84 ; Endl. 3rd Suppl. p. 36 ; 

 Post. & Rupp. p. 16 ; Kiitz. Phyc. Gen. p. 378, t. 46, f. 6 ; Hurv. 

 in Mack. Fl. Hih. part 3, p. 204 ; Harv. P. B. plate 80 ; Harv. 

 Man. p. 159 ; Eai-v. Syn. p. 129 ; Atlas, plate 49, fig. 223 ; /. G. 

 Agardh, Sj). Gen. Alg. vol. ii. p. 95, 



Ceramium plumo sum. —Roth, Cat. Bot. vol. iii. p. 133 ; Ag. Dist. p. 17. 



Plocamium plurtiosum. — Lamour. Ess. p. 50. 



Fucas plumosus. — Linn. Mant. p, 134 ; Syst. Nat. vol. ii. p, 718 ; If ads. Fl. Angl. 

 p. 587 ; Gm. Hist. Fuc. p. 152 ; Fl. Dan. t. 350 ; Llghtf. Fl. Scot. 

 vol. ii. p. 955 ; WitJt. vol. iv. p. 120; Esper, Ic. Fuc. vol. i. p. 92, t. 45 ; 

 Fl. Norv. vol. ii. p. 91; Linn. Trans, vol. iii. p. 188; Tarn. Syn. Fuc. 

 vol. ii. p. 296; Turn. Hist. Fuc. t. 60 (excL var. fi) ; E. Bot. t. 1308. 



Hab. — Parasitical on the stems of Laminarice. Perennial. Summer and autumn. 

 Common on the shores of Scotland, and of the north and west of Ireland ; Holyhead, 

 gradually becoming scarcer as you proceed soiithwards, till it becomes rare, and eventually 

 disappears. 



Geogr. Dist. — Arctic, North Atlantic and North Pacific Oceans; Davis' Strait {Turner) ; 

 Iceland {(Eder) ; White Sea, Greenland, Sitka, TJnalaska (Postels and Rupprechi) ; Arctic 

 America (Richardson) ; Kamtschatka (Bongard) ; Norway and Sweden. 



Description. — Root, a small conical disc. Fronds tufted or single, 

 linear, compressed, two to four times irregularly divided from near the 

 base, three to nine inches or even a foot in length, and from one-sixth to 

 nearly a line in breadth ; all the divisions, as well as the stem down to 

 the base, closely pectinato-pinnate, with pinnate, bipinnate, tripinnate, or 

 even quadripinnate ramuli, all very patent, and very closely set ; the 



VOL. II. B 



