310 BOTANICAL GAZETTE [APRIL 
Whether this fresh water form is the same species as the marine 
form is difficult to say, but it would seem that there were differences 
great enough to make a new species. Certainly in this form there is 
much less difference in size between the central and peripheral cells than 
that figured by the Crouan brothers. Also, in quite a number of cases, 
long gelatinous looking hairs extended from the surface, and a pyren- 
oid is always present. As these points seem to be characteristic of the 
fresh water form only it seems best to separate it from JU. /ens, and to 
make a new species. 
In appearance this fresh water species resembles greatly Coleochele 
scutata, but the absence of all differentiated sexual organs, the presence 
of many chromatophores instead of one, and the fact that 4, 8, or 16 
zoospores may be found ina single cell of the thallus, all indicate 
that the nature and development are quite different from that genus. 
The disk-shaped thallus varies from 1—3™™" in diameter, and until it 
is partly grown it consists of a single layer of cells arranged in radial 
rows about a center (fg. 7). In surface view the cells near the margin 
are either square, elongated, or wedge-shaped in outline. They vary 
in length from to to 27 mw, and in breadth from 5 to 13 # 
center they are nearly circular, and their diameter is 10 to 13 / . 
cross section the appearance is reversed ; the cells near the edge yo 
short or flattened (figs. 2 and 4), and those at the middle much i‘ 
gated, their longest diameter being at right angles to the plane 0 ie 
disk (figs. 2 and 3). The whole thallus does not rene ee we 
with the substratum throughout its life, but while it is still pee 
the central cells become loosened from beneath, then increas¢ 3 the 
and number so that the whole center arches up above the level s re 
disc, and often becomes folded in circles between the center ne of 
periphery. Soon division occurs in these cells parallel to the p 
the thallus, so that at the center several layers may be ~ 
(fg. 5). ing the col 
The membrane is gelatinous, though the layer bounding he gela 
tents of the cell is more dense than other portions. Neither t either 
tinous substance nor the denser membrane shows a blue ego 
with chloriodide of zinc or with iodine and sulfuric acid. Both 
Stained with hematoxylin, but not with eosin. = periclial 
So far as was observed, after the first few divisions sie d in this 
divisions occurred ; even new radial rows of cells aogier” the 
way, one or more projections, occurring on the exterior : 
see pet 
