706 
IX. ALGA3. 
[Catenellcr. 
A genus of a single species. 
C. Opuntia, Grev. ; — FI. N. Z. ii. 254. Roots tufted, matted, 
creeping. Frond |-1 in. high, sparingly branched, forming strings of ob- 
long internodes, varying in length and breadth, terete or compressed a little. 
— Harv. Phyc. Brit. t. 88 ; J. Ag. Sp. Alg. ii. 352. 
Bay of Islands, J. I). H. (Europe, Australia.) 
89. DUMOI7TIA, Lamouroux. 
Frond dull red-brown, cylindric, tubular, full of watery fluid, with a central 
stem and alternate simple or forked branches ; walls membranous ; inner 
surface of longitudinal filaments formed of elongated cells, outer of minute 
closely-packed roundish cells. Spores obovate, in minute clusters on the 
inner wall of the frond or in conceptacles. Tetraspores roundish, amongst 
the cortical cells. 
A small genus of annual, often tall Alga, found in both temperate zones. 
1. D. filiformis, Grev.; — FI. N. Z. ii. 254. Frond tender, mem- 
branous, 2-18 in. long, usually undivided, but sometimes divided from the 
base, narrowed at both ends, pinnated with numerous alternate long, simple, 
or forked branches, each like the main stem, yellow-greenish or purplish, 1 
line to ^ in. diameter. Conceptacles scattered over the whole frond. — FI. 
Antarct. i. 189 ; Harv. Phyc. Brit. t. 95, et Suppl. t. 357 ; J. Ag. Sp. Alg. 
ii. 349. 
Tidal rocks, Cape Turnagain, Colenso. Campbell’s Island, J. D. IT. (Europe, Aus- 
tralia.) — A very variable plant ; in Europe the fronds are sometimes compressed, curved, 
and twisted. 
2. D. cornuta, Hook. f. and Harv. FI. Antarct. i. 189. Frond tufted, 
2-3 in. long, irregularly constricted here and there, £ in. broad, brownish- 
red, naked below, above with crowded fascicled or 4-farious branches ; 
branches spreading, forked, flexuous ; branchlets recurved, ultimate attenuated 
at both ends with acute apices. — J. Ag. Sp. Alg. ii. 350. 
Campbell’s Island, Lyall. 
3. D. pusilla, Montagne in Voy. au Pole Sud , 105. t. 13./. 2. Frond 
1-2 in. long, cylindric, loosely branched ; branches forked at the apex, clothed 
with short 2-nate branchlets. Tetraspores globose, scattered or arranged in 
lines. 
On Gigartina Ancistroclada , Akaroa, D’Urville. 
90. SPYRIDIA, Harvey. 
Frond rose-red, filiform, pinnately decompound, articulated, formed of a 
wide tube, coated below and at the nodes, or all over, with a layer of minute 
coloured cells; branches and branchlets covered with minute articulated setae. 
Conceptacles naked or involucrate, terminating short branches, containing 
