MARINE ALGA OF BEAUFORT, N. C. 395 
carried the species over the unfavorable seasons at Beaufort. The rocks on which 
Dictyota and Padina grew the preceding summer and on which they occurred abund- 
antly the following summer were carefully searched by the author under favorable 
conditions in April, 1908, without revealing a trace of these species. It is probable, 
however, that a microscopic examination would show these and other alge present on 
the rocks below low water. 
It is interesting to note that, although cystocarpic and tetrasporic plants of Hypnea 
are present in the summer in about equal numbers, a collection of 55 plants of this species 
taken at random in October showed 45 tetrasporic plants and ro sexual ones, and all 
the fruiting plants observed in April were tetrasporic. Lewis (1914) has shown that the 
preponderance of tetrasporic plants in the early summer exhibited by the annual red 
alge at Woods Hole is due to the fact that the two generations are produced alternately, 
the last crop of the summer being prevailingly sexual, and the carpospores borne by this 
crop producing the sporelings whose holdfasts persist through the winter. The peren- 
nial algze at Woods Hole show no such discrepancy in the numbers of sexual and tetra- 
sporic plants. In the present instance it seems that the tetrasporic plants of Hypnea, 
a perennial species, are themselves more resistant to cold than the sexual plants. Fur- 
ther studies are needed on this subject both here and in other regions. 
The seasonal life cycle of Fucus may be summed up here for comparison with other 
regions. Young plants were observed in April along with large, old, sterile plants. The 
swollen receptacles become evident about June, but remain small and inconspicuous 
during July, becoming gradually larger and more conspicuous during August and Sep- 
tember, and reaching full size about the latter part of October, the plants showing large, 
well-developed fruits from November to January or February. After this time all 
plants observed were sterile. 
It is of interest to note that in May, 1907, when Beaufort Harbor bore almost 
entirely a spring flora, the coral reef offshore bore such strictly southern forms as Udotea, 
Dictyota, Zonaria, Nitophyllum, Chrysymenia, and others, along with the spring species 
of Dasya and Grinnellia, although at this time the water at the depth of this reef was at 
a lower temperature than that in the harbor. The explanation of this can not be given 
surely without further study, but certain differences between the harbor and the reef 
are evident. The greater clearness and higher salinity of the water over the reef probably 
play a part, but the chief factor probably is that the water at the depth of the reef, as 
may confidently be believed, does not fall to the low temperature found in the harbor in 
winter. This suggestion is supported by the species found on Bogue Beach during the 
winter from December, 1908, to March, 1909. Besides the species growing in the harbor, 
there were found during this time Zonaria flava, Z. variegata, Nitophyllum medium, 
Polystphoma havanensis, and Spermothamnion investiens. The Zonaria variegata and 
Polysiphoma havanensis were found only once and may have been brought here by the 
Gulf Stream, but the other three species were not uncommon and may confidently be 
believed to have come from the coral reef offshore. Codium tomentosum was collected 
in December and April but not in the intervening months, while Dictyota was not 
found there until after its occurrence in the harbor in June. Data concerning the condi- 
tions and alge occurring on the reef in winter would be of considerable interest, since it 
seems very probable that several species persist there throughout the year. 
110307°—21——26 
