MARINE ALGA) OF BEAUFORT, N. C. 381 
The 124 identified species and varieties recorded for Beaufort have been found as 
follows: 
Number. | Per cent. 
era watt ratie reser OE (GE ale wy aetiete «= Heteiciare es ctelelerale e|« = = bicisis,aidieis Son te sta inrshilo nis bs elele’a gig siniale.s theiotm binin’s idiots a's pin 77 62.1 
SEO WATE Osh y OM ENE COCA VECIS (ABLE 2) rccist create vatele/atolerelcistetel startet clsteialctolaperatitatatet efa'ete's elsia,sietalebaralsynve/arniate\sia aiece/eis'p 29 23-4 
ROcetirratl oustal Oe AOR MEA HCACK CLADIC SG) | rare ohrisleateisleloiatelsfelotalatcleteteteteleteteletete sinteisiaceia sists tecraieralecsialersleiaintetela sisiniate 18 14-5 
As with other plants, two factors determine the algal flora of any region. First, the 
conditions prevailing at any place naturally exclude all species which are not able to 
grow under those conditions; second, of the species which are able to grow in any 
locality, only a part find access to the region and arrive there under conditions favorable 
for obtaining lodgment. We may be certain that there are hundreds of other species 
that could grow at Beaufort if they should be carried there. Since, with marine alge, 
artificial means of transport are usually excluded, the flora which we find in any locality 
favorable for the growth of alge is determined to a considerable extent by the direction 
of the currents bringing fruiting plants, fragments, or spores of algae from other regions. 
Occasionally, however, an alga may be introduced into a regicn by artificial means. On 
one occasion there was found in Beaufort Harbor a fragment of Halimeda sp. ‘This 
seemed a very interesting discovery until it was noticed that there was in the harbor at 
that time a boat from the West Indies bearing tropical-shells and other marine objects 
for sale. To this boat we may confidently ascribe the presence of the Halimeda. 
Although this species of alga did not establish itself at Beaufort, its presence there 
showed the possibility of the distribution of alge by artificial means of transport. 
There is evidence that at least one species has established itself at Beaufort during 
the progress of these studies. Rosenvingea orientalis, known elsewhere in North America 
only from Guadaloupe and from Wrightsville Beach, N. C., was first found on Bogue 
Beach in September, 1905, and was not observed in the harbor during that year. The 
following summer, however, this species was found growing between Fort Macon jetties 
and on the sea buoy, and in the summer of 1907 it was found on Shackleford jetty as 
well as on Fort Macon jetties. The records indicate similar facts for a few other species, 
but are not sufficiently complete to warrant conclusions about them. Miss Dunn (1917) 
has presented convincing evidence showing that one species of alge, Dumontia 
filiformis, appeared on the coast of Maine and established itself there between the years 
1909 and 1913. ‘This species seems now to have spread in considerable abundance 
along a large part of the New England coast. 
Several species have been found growing in Beaufort Harbor on only one occasion. 
Such species, while obtaining a foothold, seemed unable to maintain themselves, perhaps 
because of changing conditions. These may be expected to reappear at any time and 
may establish themselves. Other species have been found only occasionally, being 
represented by scattered individuals. Such species seem to be living near the limit of 
their endurance and may appear and disappear as conditions become more or less favor- 
able. Still other species, not yet observed here, may be expected to appear whenever 
chance currents bring them to this region under conditions favorable for their obtaining 
a foothold. 
