PTILOTA. 159 



V. Griffithsia. Frond articulated, dichotomous, or 



clothed with whorled, dichotomous raraelli, rose-red. 

 Favellce involucrated, sessile or pedunculate. Tetra- 

 spores sessile, on whorled ramelli. [Plate 23, B.] 



VI. Weangelia. Frond articulated, pinnate. Favellce 

 terminal, involucrated, containing tufts of pear-shaped 

 spores. Tetraspores sessile, scattered in the ramelli. 

 [Plate 23, D.] 



VIL Seirospora. Frond articulated. Tetraspores dis- 

 posed in terminal, moniliform strings. [Plate 23, C] 



VIII. Callithamnion. Frond, at least the branches and 

 ramuli, articulated, mostly pinnated. Favellce termi- 

 nal or lateral, sessile, without involucre (except in C, 

 Tarneri). Tetraspores sessile or pedicellate, scattered. 

 [Plate 23, A.] 



I. Ptilota. Ag. [Plate 22, A.] 



Frond inarticulate, linear, compressed or flat, distichous, 

 pectinato-pinnate ; the pinnules sometimes articulate. Fruc- 

 tijicaiion : 1, roundish, clustered favellce surrounded by an 

 involucre of short ramuli ; 2, tetraspores attached to or im- 

 mersed in the ultimate pinnules. Name, TTTiT^wroi^ pinnated ; 

 from the delicately pinnated frond. 



1. V. plumosa,Ju.; frond cartilaginous, decompound ; se- 

 condary branches bi-tripinnate, elongate ; pinnae and pin- 

 nules exactly opposite, the latter subulate, cellular, traversed 

 by a narrow, immersed, articulated filament ; tetraspores on 

 short pedicels, fringing the margin of the pinnules ; favellse 

 pedunculate, with an involucre of 6 — 8 subulate ramuli. 

 Harv. Phyc. Brit. t. Ixxx. ; Grev. Alg. Brit. p. 155, t. 16 ; 

 Hook, Br. Fl. ii. p. 307. Fucus plumosus, E. Bot. t. 1308. 



On the stalks of Laminarice. Perennial. Summer and autumn. 

 Northern and western coasts of Great Britain and Ireland. — Fronds 3 — 14 

 inches long, much and irregularly branched ; branches from a quarter to 

 half a line in width, attenuated upwards, patent, opposite or alternate, 

 closely set with opposite, distichous, pinnated, lanceolate ramuli, from one 

 to four lines in length, the pinnules acute, narrow-lanceolate, simple, or, 

 in luxuriant specimens, again pinnated. Favellce clustered, surrounded by 



