314 
Batters, — On some New 
When a piece of the periostracum of a periwinkle which 
has been attacked by the Alga is examined under the micro- 
scope, it appears to be almost entirely composed of the oval 
cells of the Tellamia , the filaments of which are contained 
within the membrane, the horizontal filaments creeping either 
just below the external surface of the periostracum or just 
above the surface of the chalky portion of the shell. In the 
former case very numerous short vertical branches, ending in 
a pointed apical cell, push their way downwards towards the 
interior of the shell, and, passing completely through the outer 
membrane, are stopped by the chalky shell, or, turning again at 
right angles, grow for a short distance parallel to the primary 
filaments. In the other case, i. e. where the primary fila- 
ments are situated nearer the interior surface of the peri- 
ostracum than the exterior, the vertical branches are pushed 
upwards and terminate at the exterior surface of the mem- 
brane, which becomes quite rough and irregular, owing to its 
being pierced by the very numerous branches of the parasite. 
These vertical branches are frequently so close together 
that they appear to form a more or less parenchymatous 
membrane. 
The branching of Tellamia contorta is so irregular as to defy 
description, appearing to run in all directions, and so closely 
are the various individual plants packed together and their 
branches so interwoven that it is almost impossible to say to 
which individual a particular branch belongs, the branches in 
many cases apparently, and perhaps really, anastomosing. 
In addition to the ordinary cells, which are usually 3-6 /x in 
diameter and either oval or roundish, very much enlarged 
cells occur at irregular intervals in the moniliform filaments. 
These enlarged cells are either solitary or from two to a dozen 
or more together, and are always of a darker colour than the 
ordinary cells near them. These swollen cells do not appear 
to have any connexion with the reproduction of the plant, and 
are in all probability analogous to the enlarged cells in 
Ostreobium Queketti. They vary a good deal in shape, but 
are usually oval or elongated, and are sometimes 40 /x long by 
