434 
PACIFIC SCIENCE, VoL VIII, October, 1954 
ficato, complanato, subflabellato, undulato, 
ope disci parvi adnexo; ramificatione fere 
baud regulariter palmato flabellatoque, divi- 
sionibus ultimis brevidactyloidiis, minus 
quam 1 mm. lads, at parte kminarum in- 
feriori baud regulariter divisa 1.5-2 cm. lata; 
superficie multa excrescentia bumilia, sub- 
acuta babente; crassitudine de 2 mm. infra 
ad 250 II supra; cortice e filamentis brevibus, 
dicbotomis cellularum rotundarum in strato 
exterior! cellularum anticlinaliter elongatarum 
7-10 fjL longarum, 2.5-3 m latarum terminante. 
Tballus forming a ruffled clump 6-9 cm. 
bigb, pink in color, lubricous, lightly calcified 
throughout the inner region, complanate, 
subflabellate but not plane, attached by a 
small disc, expanding abruptly from a short 
stipe about 1.5-2 mm. long; branching pri- 
marily irregularly palmate-flabellate, the ul- 
timate divisions short-dactyloid and less than 
1 mm. wide, but the lower, irregularly divided 
portion of blades 1.5-2 cm. wide; surface of 
mature plants provided with numerous low, 
subacute excrescences, some of which become 
short, coarse, simple or palmately lobed 
branchlets; thickness variable from over 2 
mm. below to 250-300 m in upper parts; 
transection showing a broad, loose, filament- 
ous medulla and a thin, dense cortex of short, 
3-4 times dichotomous filaments of rotund 
cells 7-12 ju in diameter ending in the outer 
cortical tier of anticlinally elongated cells 7-10 
H long, 2.5-3 M wide; gland cells not apparent; 
gonimoblast characteristic of the genus; an- 
theridia borne on carposporic plants, pro- 
duced solitarily on simple or irregularly 
branched, anticlinal cortical cells, about 2 ju 
in diameter; tetrasporangia unknown. 
type: Holotype is Dawson 11444, Mar. 17, 
1953, in the U. S. National Herbarium. 
Type Locality: On coral fragments in 2-3 
m., Sta. 2. 
In his recent treatment of this genus, B0r- 
gesen (1949) recognizes five species, T.ptkeana 
from Mauritius and Ceylon, T. incrustans from 
Florida, T. weberi from Indonesia, T, mauri- 
tlanum from Mauritius, and T. calcareum from 
Ponape. In habit my plants approach T. weberi 
most closely, but show a more flabellate and 
ruffled form with more shortly digitate ul- 
timate segments. Structurally they disagree 
with that species in the presence of the outer 
cortical tier of elongate free cells and in the 
apparent lack of yellow gland cells. The pres- 
ence of antheridia on a carposporic plant is 
notable, and it may be pointed out here that 
in none of these several species have tetras- 
porangia been reported. Furthermore, the cal- 
cified condition and the involucral branches 
surrounding the gonimoblast, arising from 
the auxiliary cell, appear to be unique in 
Titamphora among the genera of the Nema- 
stomaceae (Feldmann 1942^^: 112). A study of 
the life cycle in this genus seems to be called 
for to confirm or deny its assignment to the 
Nemastomaceae. 
Key to the Species of Hypnea 
1 . Thalli mainly erect and free, not repent or 
turf-like . 2 
Thalli mainly repent, forming a loose or 
compact turf; sometimes semi-erect in H, 
esperi, but only to 3 cm. high. ....... .4 
2. Branches bearing small, stellate, spinous 
processes ................ ,H. cornuta 
Branches bearing simple or branched, but 
not stellate, branchlets ............... 3 
3. Ultimate lateral branchlets exceedingly 
abundant, dense, short, often bifurcate. . 
...................... H. boergesenii 
Ultimate lateral branchlets not dense or 
crowded, mostly long, slender, not bifur- 
cate H, valentiae 
4. Plants small, the branches 250-500 ii in 
diameter . H. esperi 
Plants larger, the branches 700-2,500 /x 
in diameter . 5 
5. Plants loosely matted; tetrasporangial sori 
encircling small branchlets . 
H. cervicornis 
