36 Rhodora ! [Marcu 
Rosenvinge, Grønlands Havalger, p. 786, 1893), this tendency to 
confuse the two plants while collecting may explain the unnoted 
presence of the former species on the coast of New England previous 
to 1913. The discovery at Newport, R. I., may further indicate 
that additional localities, both north and south, remain to be dis- 
covered. The seasonal behavior indicates the temperatures of 10° C. 
to 20° C. as those critical for the fruiting of this species, covering 
both the production of cystocarps and of tetrasporangia and suggesting 
that 10? C. to 15? C. may be the temperatures favorable for cysto- 
carpic reproduction (gametophyte) and 15? to 20? C. for tetrasporic 
reproduction (sporophyte). 
It is to be noted that Dumontia filiformis is credited with possessing 
a prostrate perennial basal portion (cf. Reinke, Algenfl. westl. Ostsee, 
p. 204, 1889, and Brebner, Journ. Linn. Soc., vol. 30, pp. 436-443, 
pl. 35, 36, 1895). Dunn neither makes mention of this in the New 
England plant nor reference to the various accounts of its significance, 
persistence, and special structure, although her figures (loc. cit., pl. 19, 
figs. 8, 9) of the holdfast indicate that her plants possessed a basal 
portion of more complicated structure than that of an ordinary discoid 
holdfast My own specimens show something of this prostrate 
thallus, but it is desirable that our New England plants be studied 
more in detail in this respect. 
Brebner (loc. cit.) and Oltmanns (Morph. u. Biol. d. Algen, I, 
p. 573, fig. 356 a, 1904) have given a different interpretation to the 
structure of the apical meristem of the European plant from that of 
the American plant as indicated briefly by Dunn (loc. cit., p. 436), 
but her figure (pl. 19, fig. 11), although taken in all probability from a 
fairly mature branch, is more consistent with what is indicated for the 
European Dumontia filiformis than the type of apical meristem re- 
presented by Furcellaria fastigiata (cf. Oltmanns, loc. cit., p. 545, 
fig. 329). 
The points as to identity in structure and development of the plants 
ascribed to Dumontia filiformis of the Atlantic Coast of Europe and 
North America are not completely settled as yet as I have shown by 
indicating our lack of knowledge as to details of agreement or dif- 
ference in connection with the prostrate thallus and the apical 
meristem. As to the specific identity of the plants of the North 
Pacific with those of the North Atlantic, the question has been raised 
by Kjellman (loc. cit.), as indicated previously. "There seem possibly 
