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. Id). By extending a little beyond the plane of the lamina, 

 at its edges this groove next originates beside it two lateral 

 ridges (fig. \e). At first faint, these are soon made prominent by 

 thickening and the formation of sclerenchyma 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. \g)- This appears most prominentlv 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. 1 h) 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 

 Pleurophycus, 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 paraphyses 

 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 paraphyses 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 pcrsistance and large size of the 

 primary one-layered lamina, a character, the significance of 

 which in the ])h\-l()gcn\-, I am not prepared at this time to es- 

 timate. 



