DUBLIN UNIVERSITY ZOOLOGICAL AND BOTANICAL ASSOCIATION. 141 
2.—CoTHURNICELLA, U. 0. 
Cells in simple rows, each row arising from the side of a joint of an 
articulated stem, each cell springing from the upper and back part of 
another by a short horny tube. Cells all facing the same way. 
Cell-mouth provided with a movable operculum. Ovicell an ordi¬ 
nary cell of a series, much enlarged, but scarcely modified in form. 
C. dcedala, n. s. Plate XI., Pigs. 3 and 4. 
The only known species. 
This genus seems to have a sufficient number of characters in com¬ 
mon with Catenicella to warrant its admission into the same family. It 
is, however, at once distinguished from the rest of the Catenicellidse by 
its simple rows of cells arising regularly from the joints of an arti¬ 
culated stem. The joints of this stem appear to be abortive cells. 
The last joint of one branch is often dilated into a cell, while the 
other branch ends in a single or double tendril of narrow joints, and the 
final cell of a row is frequently capped by a similar tendril, representing 
a continuation of the series. In C. dcedala the stem is at first simple, 
then makes a single bifurcation, and the cells start in straight rows, a 
row from the inner aspect of each joint of each branch, so that the tri¬ 
angular space within the fork is closely strung, like a harp, with pa¬ 
rallel strings of cells (Plate XI., Pig. 3). The anterior aspect of the cell 
is narrow and slipper-shaped. 
The mouth is placed near the top of the cell, large and crescentic, with 
a thin projecting upper rim. A movable semicircular operculum, with 
a raised edge, covers, or hangs below, the cell mouth. The operculum 
has at its base on either side a projecting triangular catch, which fits 
into a notch in the lip. One would almost expect this apparatus to 
shut with a snap like the clasp of a purse, it is so nicely fitted, and so 
eminently mechanical-looking. 
Below the cell aperture a long, depressed area stretches nearly to the 
base of the cell. The cell is much compressed laterally; the side view 
is much broader, and almost reniform. The cell-wall is double through¬ 
out, with a wide space between the layers, thus forming two distinct 
chambers, the inner not even resembling the outer in form. The ante¬ 
rior depressed area is formed by the outer layer alone, so that beneath 
there is still another space before reaching the inner wall. In the cen¬ 
tre of the area a tube passes through this space, uniting two correspond¬ 
ing apertures, one in either membrane, and thus communicating di¬ 
rectly with the interior of the cell. The side view shows the inner 
chamber as a doubly bent expansion of the common tube of the ccenoe- 
cium. 
Here and there one of the cells of a row is about double the size of 
the rest. These large cells have their opercula always closely shut. They 
are slightly more gibbous than the others, but scarcely differ from them 
in form. They are, doubtless, the ovicells. 
VOL. v.—proc. soc. u 
