1923] Setchell,—Dumontia filiformis on the New England Coast 35 
The appearance of this plant, long sought for, on the eastern coast 
of North America, in such abundance at two localities on the Maine 
coast suggests, as Dunn has indicated (1917, pp. 425 and 459), that 
it is a recent introduction. "The vicinity of the Harpswell Laboratory 
had been carefully explored in the early part of July by Frank S. 
Collins for six seasons (viz., 1902-1905 and 1908-1909) without 
Dumontia having been detected. Dunn, consequently, suggests that 
it had become established somewhere between 1909 and 1913. The 
discovery of Dumontia filiformis, well established, on a portion of the 
New England coast so remote from the Maine coast as Newport, 
R. I., seems to indicate that it has been much longer in residence on 
the New England coast, but has been overlooked. In its July state 
it resembles closely passé plants of Halosaccion ramentaceum (L.) Ag., 
and may have been passed over even by such an experienced collector 
as Collins as unworthy of closer examination. 
Dumontia filiformis, formerly credited with a wide distribution, 
occurs on the Atlantic coasts of Europe, on the northeast and north- 
west coasts of North America, and on the northeast coast of Asia. 
Cotton (Journ. Linn. Soc., Bot., vol, 43, p. 202) has examined the 
specimens from the Falkland Islands and from the New Zealand 
region which have been credited to Dumontia filiformis and finds 
that they are all different, even generically. As he says (loc. cit.),— 
“There is now no evidence that Dumontia filiformis occurs at all in 
the Southern Hemisphere." 
On the Atlantic coast of Europe Dumontia filiformis ranges from 
the region of the English Channel to the northern coasts of Norway 
and thence east to the Murman Sea, but in more northern waters is 
only occasional and inhabits sheltered localities. Since it grows in 
shallow tide-pools, the water surrounding it is commonly raised in 
temperature by insolation. It occurs on the southwest coast of 
Iceland. It is still a question as to whether it is to be classed as an 
inhabitant of the west shore of Greenland. The specific identity of 
the plant of Bering Sea has been called into question by Kjellman 
(Om Beringh afvets Algflora, p. 30, 1889), but the relationship is 
very close, if not identical, with Dumontia filiformis. The plant of 
the Kurile Islands, Asia, is similar to that of the Bering Sea coasts of 
North America. 
Since there has seemingly been confusion between Dumontia 
filiformis (Huds.) Grev. and Halosaccion ramentaceum (L.) Ag. (cf. 
