March, 1907.] Cymathere, a Kelp from the Western Coast. 
93 
The smallest specimen which could be certainly identified 
was about 7 mm. long (fig. 4). In this the stipe was only very 
slightly longer than in the smaller specimen, being still less than a 
millimeter while the lamina had become much longer. From 
this period on through life the species is characterized by a long 
narrow lamina on a very short stipe. In the center of the lamina 
has appeared a band of tissue several cells in thickness, which 
extends from the transition region, where it narrows into the 
stipe, in an oblong patch through the middle of the blade to 
within about 2 mm. of the tip. 
This thicker area soon cuts off and separates the original 
thinner portion from the growing point in the transition region 
and pushes it out into the end of the lamina. This action does 
not, however, as might be supposed, presage the speedy disap¬ 
pearance of the primitive thin region. On the contrary it shows 
itself able to make good the waste of erosion for a long time and 
even increases very much in size. At the first appearance of the 
thicker band its area is only about G sq. mm. while in a specimen 
about 5 cm. long (fig. 8) it covers 180 sq. mm. forming a wide 
ruffle all around the tip of the lamina. It continues to be found 
on specimens even longer than 200 mm. (225 is the longest of 
such in my collection) but greatly eroded though still giving 
evidence of continued growth. The presence of a lamina one 
cell in thickness has been noticed by Setchell '05 who gives a 
summary of the cases in which it is known to occur. These are 
Laminaria saccharina, Saccorhiza dermatodea (Setchell ’91) and 
A lari a esculenta all of which Setchell himself has seen, though 
the case of Laminaria was earlier described by Reinke and per¬ 
haps by Kuetzing whose determination, however, Setchell ques¬ 
tions. From these cases Setchell infers that such a stage is 
common to all of the Laminariaceae. Though not so described 
by MacMillan ’99, Nereocystis has the same manner of growth. 
The writer has in his collection a plant 4 cm. in length in which 
the pneumatoeyst is just beginning to show as a darkened area 
slightly different to the touch, and a very faint short depression 
already marks the beginning of the first split. In this specimen 
there is a margin extending around the tip and half wav down 
the blade about 1 mm. wide, of thin tissue exactly as in Cyma¬ 
there. In Saccorhiza as figured bv Setchell ’91, the primitive 
blade persists only till the plant is about 7 cm. long. I am in¬ 
debted to Professor Setchell for the information that nearly 
all the plants from the northwest coast labelled by Harvey 
Alaria marginata are young specimens of Cymathere, a designa¬ 
tion which may well have been suggested by the long persisting 
remannts of the embryonic lamina. All this would indicate 
that the large size attained by the one layered lamina in Cyma¬ 
there is quite exceptional. 
