94 
The Ohio Naturalist. 
[Vol. VII, No. 5, 
The first indications of the folding characteristic of the genus 
appear in a specimen 45 mm. long. The exact manner of the 
folding can not be well made out at first but in a specimen a 
little larger, where it is more extended, it is seen to consist of a 
faint downward bending into a groove in the middle of the lam¬ 
ina (fig. 1 d). By extending alittle beyond the planeof the lamina, 
at its edges this groove next originates beside it two lateral 
ridges (fig. le). At first faint, these are soon made prominent by 
thickening and the formation of sclerenehyma along their length 
(figs. 1/ and 9). In specimens about 20 cm. long the first in¬ 
dications of the third ridge begin to appear in the flattening and 
finally in the bending upward of the middle of the original median 
groove (fig. lg). This appears most prominently in the middle 
of the lamina and fades out both toward the tip and base, a 
condition which obtains even in specimens half a meter long, in 
which the third ridge does not attain its full development for a 
distance of 10 cm. from the base; and even in large specimens the 
two lateral ridges may extend closer to the base than does the 
central. Gradually, however, it also extends downward till this 
indication of its later origin is lost. Meanwhile this ridge is 
thickened and strengthened (fig. Hi) as were the first two; and the 
grooves between it and the lateral ridges have given rise to two 
more ridges on the reverse side of the lamina which are in turn 
similarly thickened. Just as the edges of the first groove made 
the two lateral ridges, so the edges of these may bend down be¬ 
yond the plane of the lamina forming on the reverse side two 
additional ridges which may be thickened (fig. 1 i) so that the 
lamina has sometimes three and four ribs instead of three and 
two. This condition I have seen only in a very old specimen 
toward the base; at the tip the extra ribs faded out showing in 
the process all transitions and clearly indicating the manner of 
their formation. 
This study would seem to show that Cymathere is not like 
Pleurophvcus, as might have been supposed, probably a deriva¬ 
tive of the Laminarias by the development of the folds in the 
lamina. Its simple holdfast seems to be the external indication 
of a structure in all respects simple and low in the scale, though 
not necessarily primitive. Its linear unthickened paraphvses 
together with the poor development of mucilage ducts and pith- 
web would indicate that like Saccorhiza and Phyllaria it probably 
branched off from the main phylum of the Laminariaceae before 
the habit of producing clavate thickened paraphvses and a 
holdfast of secondary hapteres became ineradicably fixed as it 
is in the higher kelps. In its development nothing noteworthy 
was found except the very long persistanee and large size of the 
primary one-layered lamina, a character, the significance of 
which in the phylogenv, I am not prepared at this time to es¬ 
timate. 
