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ERYTHROTRICHIA 74 
representing coalesced branches, the cells later often irregularly 
arranged and the broader parts 3-6 cells wide and 2 or 3 cells 
thick, the base commonly remaining unicellular and the apices 
of a single series of cells; cells extremely varied in form, mostly 
7-14 іп maximum diameter. The plants appear to be quite 
distinct from those that we have referred to G. Alsidii, in form 
and structure and also in color, so far as the last-mentioned char- 
acter may be determined from formalin-preserved specimens, the 
С. Сотпи-сетљ being apparently greener and darker. The outer 
gelatinous walls are much attacked and surrounded by bacteria 
in both old and young individuals, but this may have little sig- 
nificance, as other attendant epiphytes are attacked in a similar 
way, though in a less degree. 
ERYTHROTRICHIA Aresch.; Fr. Summ. Veg. Scand. 132. 
1846; Phyc. Scand. Mar. 209. 1850 
Erythrotrichia polymorpha sp. nov. 
The strongly developed basal disc suborbicular or oblong, 
attaining often a diameter of 150—600 и, closely adherent or in age 
more or less free at the margins, the younger discs monostromatic 
throughout, the older becoming irregularly distromatic in the 
central portions and at length giving rise there to few or many 
erect filaments, these finally, in some cases at least, becoming 
ribbon-shaped fronds; marginal cells of disc at first cuneate and 
often emarginate or furcate, becoming mostly oblong or linear- 
oblong and 13-30 и X 5-8 и, those of central portions irregularly 
quadrate, ovoid, or suborbicular in surface view, 8-16 џи іп diam- 
eter, often vertically elongate, clavate, and 20-40 и high; erect 
fronds, when well developed, at length narrowly linear from a long- 
pedicelled base, attaining a length of 0.25-1.3 mm. and a maximum 
width of 35-85 и, tapering very gradually to the base and a little 
less gradually to the apex, finally 8 cells in width and mostly of a 
single layer of cells or now and then irregularly bistratose, the cells 
usually in rather regular transverse rows, the margins plane, entire 
or lightly undulate, the pedicel 8-18 и broad, of 5-25 cells in a 
single series; cells of frond at first quadrate-oblong or discoid, 
finally ovoid and mostly 6-11 и in vertical diameter; spores borne 
either upon the disc or upon the erect fronds, ovoid, 8-14 ш in 
greatest diameter. [PLATE 29. 
Chaetomorpha cartilaginea and Cladophora fascicularis, 
collected on surf-washed rocks, Chincha Islands, June 18, 1907, 
