56 The Botanical Gazette. [February, 
opposite end of the flask-shaped cell is usually closed and 
not connected with any other cell (fig. 5, 4). (c) In the 
central part of the medullary layer between the flask-shaped 
cells there are many oblong, thin-walled cells running at right 
angles to the direction of growth. Occasionally they are found 
singly, but more often there are several united, forming 4 
chain which often reaches across the medullary part (fig. 5, 4)- 
There is no difference in structure between the midrib and 
the rest of the blade. The greater thickness of the midrib 
is caused by an increase in the thickness of the medullary 
layer (fig. 2). 
The reproduction of this plant is in no way different from 
the other species of the Laminariacee. Unicellular zoospo- 
rangia protected by paraphyses are borne in large irregular 
patches on every part of the blade. In some luxuriant indi- 
viduals I have found the patches of zoospores extending upon 
or even across the midrib. The zoospores are evidently de- 
veloped from the epidermal cells, for we find in cross-sections 
of fruiting specimens the outer row of small hypodermal cells 
just beneath the zoosporangia (comp. figs. 3 and 4, 7). 
A study of the stipe reveals an entirely different structure. 
It is very tough and rigid, and is composed entirely of cells 
which are about twice as long as broad, and much smaller 
in the hypodermal than the medullary region. In fact in 
many of the sections there seems to be, especially in the hy- 
podermal region, little or no space between the cell walls. 
The epidermis of the stipe is composed of very irregular thick 
walled cells, the walls of which are of a brownish color (fig- 6). 
In the rootlets, especially towards the apex, the cell walls 
are much thinner, the cells larger and longer (fig. 7): - 
NOMENCLATURE.—In looking up the descriptions of the 
two recognized species of Costaria I find that the names of 
the two have been changed several times without right oF 
reason, for so doing. As we are gradually approaching @ 
stable nomenclature, it seems proper that at this time We 
should restore to these plants the names which rightfully 
belong to them. 
The common species on the Californian coast has been called 
Costaria Turnert Grev. It is not, however, Costaria Tur- 
nert Grev., but Costaria Mertensii J. Ag.? 
nl 
?Species, genera et ordines Algarum 1: 140. 1848.—Neither should the name 
be written Costaria Mertensii (Mert.) Post & Rupr. as Kjellman has done ® 
Engler & Prantl’s Pflanzenfamilien 1*: 257. 
