128 
If we examine thè thallus from above (fig. 3 b) we find that it ìs 
composéd of numerous rows of cells radiating flabelliform out from 
thè margin; along this we find a series of very large top cells and 
these divide themselves gradually by longitudinal and transverse 
walls, each in this way giving rise to 2 - 4 rows of cells. In a tran- 
sverse section (fig. 3 a) we find that thè thallus consists of a me- 
dullary layer of very large cells with dark brown contents in thè 
middle, and one or two, on thè upperside seldom even three, large 
fiat cells; at thè surface on both sides an epidermal layer of small 
cells. The large fiat cells nearest thè periphery are most often, in any 
case in older parts of thè thallus, divided by vertical, secondary walls 
into two - four cells, more seldom horizontal walls also occur. 
A transverse section (fig. 3 c) shows thè development of thè 
thallus. First by a vertical wall a large celi is cut off from thè topcell 
and at thè new cell’s upper - and under side two fiat cells are formed 
from which thè epidermal layer has its origin, thè cells on thè upper- 
side being gradually divided into 4 - ó small cells those below most 
often only in two or not at all. From thè large celi in thè middle 
one, two or sometimes even three fiat cells are cut off on thè upper- 
side, one or sometimes two from its underside. VVhile these cells 
on thè side below most often are undivided, sometimes though divi- 
ded by a vertical wall into two cells, those on thè upperside are 
somewhat more divided especially thè uppermost cells. The large 
cells in thè middle are sometimes also divided by vertical walls into 
two cells (thè two cells to thè right in fig. 3 a). 
The rhizoids are outgrowths from thè epidermal cells below. 
Upon thè upperside of thè thallus here and there scattered groups 
of hairs occur; thè hairs have their origin from epidermal cells (fig. 3 d). 
I may also point out that all my material was sterile. 
As will be clear from this description, my plant quite agrees 
with that of Sauvageau, only that it is sterile, and this I have also 
found by comparison of thè material of thè Canary plant. 
As already emphasized by thè quotation above, it seems to me 
that thè Ralf sìa ceylanica Harv. described and figured by Miss E. Barton 
(Mrs. Gepp) 1. c. bears a great likeness with ours ( A ). Some differ- 
( 4 ) In a later paper : « Marine Algae (Chlorophyceae and Phaeophyceae) and 
marine Phanerogams of thè « Sealark » Expedition (Transact. Linn. Soc. voi. XII 
