192 Phillips. — The Development of the Cystocarp 
the whole area round the spot where the fertilized procarp 
lies increases in thickness by the cutting off of pericentral 
cells, in which divisions occur parallel to the surface, giving 
rise to vertical rows of cells. The peripheral cells, derived 
from the pericentral cell which bears the fertilized procarp, 
do not take part in this vigorous growth, but remain in 
number as at the moment of fertilization. They however 
enlarge considerably, and assume a characteristic appearance, 
which is the first indication as to which procarp has been 
fertilized. The rows of cells surrounding these sterile deri- 
vatives arch over them, leaving a central depression which 
is the carpostome. Pressed by the convergence of the adjacent 
filaments, the sterile cells, which are five in number, become 
pyriform, with their pointed ends outwards, and their walls 
become at the same time thickened and highly refractive. 
Fig. 2 7 , which represents this stage in Nitophyllmn Hilliae , 
might also serve for D. sinuosa. 
The pericentral cell cuts off a segment, which is the auxiliary 
cell, and from which later the gonimoblast-filaments arise. 
The sterile cells are then pushed off, and eventually disappear, 
supplying in their decadence a copious mucilage. 
As will be shown, in these particulars D. sinuosa more 
nearly resembles N itophyllum than the typical species of 
Delesseria . The systematic position of the species will be 
discussed later. 
Nitophyllum laceratum, Grev. 
N itophyllum laceratum may be regarded as the typical 
species for the genus as established by Greville. There is 
no percurrent midrib, and the cystocarps are embedded in 
the substance of the thallus. As it possesses, however, a 
distinct anastomosing venation in its older parts, and a more 
obscure venation throughout, it was placed by Kiitzing (’49) 
with other species like it in these respects in a genus Crypto- 
pleura , an arrangement, however, which has not found 
acceptance. 
