98 
PACIFIC SCIENCE, Vol. XI, January, 1957 
50. Branching regularly alternate and gen- 
erally spirally arranged; axes less than 
100 /a in diameter Callithamnion 
50. Branching irregular; axes over 100 /z in 
diameter Griffithsia 
51. Thalli consisting of a subcylindrical 
axis bearing coarse, angular, toothed 
lateral branches Turbinaria 
51. Thalli not as above 52 
52. Thallus net-like, at least in part. ... 53 
52. Thallus not net-like 5 5 
53. Thallus reddish, delicate, flat or four- 
sided 54 
53. Thallus brown, coarse, convoluted. . . . 
Hydroclathrus 
54. Net-like parts formed as part of flabel- 
late blades Hemitrema 
54. Entire thallus a four-sided net-like form 
around a central axis Dictyurus 
55. Thallus cushion-shaped or subspherical, 
solid or hollow, with cells of macro- 
scopic size Dictyosphaeria 
55. Thallus not as above; cells not of ma- 
croscopic size 56 
56. Thallus hollow-tubular or with hollow, 
vesicular or tubular parts 57 
56. Thallus without hollow parts 62 
57. Thallus without regular constrictions or 
cavity partitions 58 
57. Thallus regularly constricted and with 
partitions across the cavity at the con- 
strictions Champia 
58. Thalli hollow essentially throughout. . 
59 
58. Thalli consisting of a short, solid stipe 
bearing one or more hollow vesicles . . . 
Botryocladia 
59. Thallus parts long and slender com- 
pared to diameter 60 
59. Thallus parts short and inflated com- 
pared to diameter Rosenvingea 
60. Thalli reddish; the tube wall composed 
of several cell layers 61 
£0. Thalli greenish; the tube wall com- 
posed of a single layer of cells 
Enteromorpha 
61. Tetrasporangia borne in swollen, ter- 
minal stichidia Coelothrix 
61. Tetrasporangia borne in sunken cavities 
in the branches Lomentaria 
62. Thalli flat or markedly flattened, at 
least in part 63 
62. Thalli essentially cylindrical (some- 
times moderately compressed as in 
Hypnea) 75 
63. Thalli brownish or reddish, not green, 
of more than one layer of cells, at least 
at the midrib if present 64 
63. Thalli green, of a single layer of cells 
throughout Anadyomene 
64. Thallus with a midrib (note that the 
flattened blade part is very narrow in 
Taenioma) 65 
64. Thallus without a midrib 67 
65. Color reddish; branching not at all 
dichotomous 66 
65. Color brownish; branching subdicho- 
tomous Dictyopteris 
66. Apices with two or three terminal hairs 
Taenioma 
66. Apices with a naked apical cell 
Hypoglossum 
67. Thallus surface covered with tufts of 
soft but mostly erect filaments 
Dasyopsis 
67. Thallus surface without tufts of fila- 
ments 68 
68. Thalli prostrate and fastened by the 
lower surface 69 
68. Thalli essentially erect, free, not pros- 
trate 71 
69. Thalli brown 70 
69. Thalli red Rhodymenia 
70. Thalli fan-shaped Pocockiella 
70. Thalli dichotomously branched 
Dictyota (patens) 
71. Growing points not in apical pits ... 72 
71. Growing points in apical pits 
Laurencia (parvipapillata) 
72. Growing point consisting of a single 
apical cell . ..73 
