Plocamium.] 
IX. ALGiE. 
695 
pressed, linear, pinnately decompound ; pinnules short, acute, alternately 
secund in pairs or threes or fours, of 2 strata of cells ; inner cells oblong, 
longitudinal ; outer small, polygonal coloured. Conceptacles sessile or stalked, 
hemispherical, opening by a pore, containing a mass of angular spores, on 
filaments which radiate from the base. Stichidia containing oblong trans- 
versely-parted tetraspores. 
A genus of most beautiful Algce, found in both temperate zones. 
§ 1. Thamnophora, —Frond usually membranous , flat, ecostate or with a slender costa ; 
branchlets alternately in pairs ; conceptacles and stichidia axillary. 
1. P. procerum, J. Agardh ; — M. N. Z. ii. 246. Root branching. 
Frond 1-2 ft. long, linear, almost ribless, pectinate- pinnate, y-g—i in. diameter, 
bright pink; pinnae alternately geminate, lower one and divisions of the 
upper from a broad base, acuminate, subulate, entire or externally serrulate. 
Conceptacles axillary, stalked, 1-4 together. Stichidia axillary, tufted, simple, 
falcate, acute. — Harv. Phyc. Austr. iv. t. 223 ; Ner. Austr. 122. 
New Zealand, Lyall. (Australia, Tasmania.) 
2. P. Corallorhiza, Harv. FI. N. Z. ii. 245. Root branching. 
Frond 12-18 in. long, clear red, stipitate, membranous, broadly linear, in. 
broad, subcostate at the base, pinnate or 2-pinnate ; segments alternately 
geminate, lower shortly subulate, upper incised or pinnatifid ; outer margin 
of each segment serrate. Conceptacles pedicelled, and stichidia axillary, 
crowded. — Harv. Ner. Austr. 121 ; J. Ag. Sp. Alg. ii. 402. 
Dusky Bay, Forster. — Perhaps the habitat is erroneous. (South Africa.) 
3. P. costatum, Hook.f. and Harv. FL N. Z. ii. 246. Frond .narrow, 
membranous, fiat, a foot long, -A in. wide, decompoundly-pinnate, with a 
stout percurrent costa ; pinnae lanceolate, alternately geminate, lower subu- 
late, upper elongate, laciniate, falcate or straight ; outer margin of the seg- 
ments serrate. Stichidia axillary, crowded, many times forked. — Harv. Ner. 
Austr. 122 ; J. Ag. Sp. Alg. ii. 403. Thamnophora Gunninghamii, Grev. 
Common in the Bay of Islands, etc., Cunningham. (Australia, Tasmania.) 
4. P. angustnm, Hook.f. and Harv. FL N, Z. ii. 246. Frond rather 
cartilaginous, 6 in. long, in. broad, with a stout decurrent costa, decom- 
poundly pectinately pinnate ; pinnae alternately geminate, lower subulate, 
upper elongate, laciniate ; outer margin of the segments quite entire. Con- 
ceptacles solitary. Stichidia crowded, axillary. — Harv. Ner. Austr. 122 ; J. 
Ag. Sp. Alg. ii. 402. 
Common from the Bay of Islands to Otago. (Australia, Tasmania.) 
5. P. cruciferum, Harv. in FL N. Z. ii. 246. Scarcely to be dis- 
tinguished by habit or other characters from P. angustum, except in the sti- 
chidia, which are cruciform or palmately lobed, or even multi-radiate, with 
lobes short, the whole crowded with tetraspores. 
East coast, Colenso. 
6. P. abnorme, Hook.f. and Harv. FI. N. Z. ii. 246. Frond 1-2 in. 
high, narrow, slender, with an obsolete costa, pinnately decompound ; pinnae 
