302 | DR. LILY BATTEN ON 
6. P. vIOLACEA Harv. Man. Brit. Alg. ed. i. 1841, p. 92. 
P. subulata J. G. Ag. Spec. Alg. ii. 1863, p. 985 (nec Kütz.). 
Hutehinsia violacea C. A. Ag. Syn. Alg. Scan. 1817, p. 54. 
Heferences. De Toni (22) iv. p. 900 ; Falkenberg (24) p. 115 : Hauck (31) 
p. 225. 
Icones. Harvey, Phye. Brit. 1846-51, pl. 209. syn. 115. — Evsiceata., 
Wyatt, Alg. Damnon. no. 176. 
DESCRIPTION.— Habit. Plants consisting of a main axis, conspicuous at 
the base, but soon becoming alternately branched, the branches being densely 
clothed with alternate ramuli. Length usually about 12-15 cms., occa- 
sionally attaining a length of 25 cms. Siphons. 4 primary pericentral 
alternating with 4 secondary, bounded on the outside by a band of corticating 
cells. Colour. Brownish-purple. Anatomy. Articulations obscured at the 
base by the corticating cells, 2 to 4 times as long as broad in the smaller 
branches and ramuli. Attachment organ. Young plant attached by 2 or 3 
rhizoids developed by longitudinal proliferation of the pericentral siphons. 
Later, the siphons and external cells at the base all develop rhizoids, and form 
an attachment organ similar in type to that of P. elongata. Reproductive 
organs. Tetraspores borne in swollen ramuli. Cystocarps ovate, usually 
shortly stalked, with no elongation in the region of the ostiole. 
There seems to have been confusion between P. violacea and P. nigrescens, 
although the anatomy is so dissimilar. The confusion was probably due 
to a variety of P. nigrescens, which was brighter and purple in colour 
with greater delicacy of ramification, being deseribed as P. violacea by 
Harvey in Smith's English Flora (p. 332). The P. violacea Harv. has been 
ascertained by Agardh to be identical with the P. violacea. of Continental 
authors, whieh has only four primary siphons. 
P. subulata Ag. differs from P. violacea Harv. only in the degree of corti- 
cation, which seems insufficient ground for a specific distinction. 
P. VIOLACEA var. GRIFFITHSIANA, var. nov. 
P. Grifithsiana Harv. Manual, 1841, p. 91 : Phye. Brit. 1846-51, pl. 228, 
syn. 112. 
Pyramidal in form, attaining a length’ of as much as 25 ems. Axis con- 
sisting in the lower parts of 4 primary siphons and 4 secondary arranged 
round a central siphon. In the upper parts the four secondary are absent. 
Occasionally a few small corticating cells are present at the extreme base 
of the plant. Branches arising alternately, clothed with numerous ramuli 
which are sometimes dichotomously branched. 
P. VIOLACEA var. TENUISSIMA Hauck, Meeresalg. 1885, p. 227. 
P. divaricata Kütz. Tab. Phye. xiii. 1863, p. 26, tab. 84 (a-c) [ fide 
Hauck ]. 
Plants delicate with lax growth, corticate at the base. Artieulations 4 to 
8 times as long as broad, branching showing marked pseudo-dichotomy. 
