.688 
IX. ALGA!. 
\_Melanthalia. 
cells, outer of many series of most minute coloured cells. Conceptacles 
marginal, thick-walled, hemispherical ; spores on moniliform filaments, cover- 
ing a prominence on the floor of the conceptacle. Tetraspores unknown. 
An Australian and New Zealand genus. 
1. M. abscissa, Hook. f. and Haro. Ft. N. Z. ii. 242. Fronds tufted, 
blackish when dry, 2-3 in. long, fastigiately dichotomously decompound ; 
segments 2-edged ; margins obtuse, unequally thickened here and there, lower 
~ in. long, upper narrower, subcuneate below the forkings. — J. Ag. Sp. Alg. 
ii. 613. Fucus, Turn. Hist. t. 137. Chondrococcus, Kuetzing. 
New Zealand, Banks. 
2. M. Jaubertiana, Mont.; — FI. N. Z. ii. 242. Frond similar to M. 
abscissa, but larger, 4-6 in. long ; segments quite equal throughout. — J. Ag. 
Sp. Alg. ii. 613. 
Common along all the coasts. (Tasmania.) 
61. GELIDITJM, Lamouroux. 
Frond dull red or purplish, linear, compressed, pinnate, horny, solid ; axis 
of densely interlaced tenacious fibres ; walls of small polygonal cells, the 
outermost minute in horizontal series. Conceptacles 2-celled, formed of two 
opposite confluent conceptacles, immersed in swollen branchlets, containing 
oblong spores which are attached to the walls of the septum. Tetraspores 
forming sori on dilated branchlets. 
Native of both temperate zones. 
1. G. comeum, Lamour.; — FI. N. Z. ii. 243. Frond 2-6 in. high, 
between cartilaginous and horny, nearly flat, distichously branched, setaceous 
or more or less stout; branches 1-2-pinnate, linear, attenuated at each end, 
pinnules mostly opposite, spreading, obtuse, bearing elliptic conceptacles 
within their apices. — Harv. Phyc. Brit. t. 53 ; J. Ag. Sp. Alg. ii. 469. 
. Probably abundant, Hawke’s Bay, Colenso ; Banks’s Peninsula, Lyall. (All seas.) 
2. G. asperunij Grev. ; — FI. N. Z. ii. 243. Frond very variable in 
size, two-edged, decompoundly pinnate; pinnae linear, narrowed at both ends, 
rather regularly again pinnate, serrulate. — J. Ag. Sp. Alg. ii. 475. 
New Zealand, Banme (J. Agardh, 1. c.) (Australia.) 
62. CATJLACANTHUS, Kuetzing. 
Frond purplish-brown, black when dry, terete, excessively branched; 
branchlets aculeate, cartilaginous ; axis of young parts tubular, of a single 
flexuous articulate tube, giving off alternate branches which divide excessively, 
their divisions becoming packed and forming the surface ; adult part alto- 
gether cellular. Conceptacles unknown. Tetraspores in slightly swollen 
branchlets, sunk in the cortical threads, transversely divided. 
A curious genus, of a N. Atlantic species and the following. 
1. C. spinellus, Kuetz. ; — FI. N. Z. ii. 244. Fronds lf-1 in. long. 
