148 ZOOPHYTOLOGY. 
group, or an aberrant species of the genus Calpidium. As 
in Calpidium, the cells have two “ key-holes;” but a sigle 
glance must satisfy us that the cell consists of a primary and 
a secondary chamber, bearmg the same relation to one 
another that the two cells of a germinate cell bear at a bifur- 
cation in any of the other species of the genus. C. geminata 
bifurcates at every cell, so that all the axial cells are germi- 
nate. The septum between the cells is traced on the back 
of the cell by a deep groove in the usual position. The back 
of the primary cell, both in this species and in C. aurita, is 
frequently perforated to give origm to a horny, tubular 
tendril. The secondary cell sometimes gives off a secondary 
axis, but more usually only a single wedge-shaped cell, 
apparently partially abortive. The ccenccium is very cal- 
careous, and becomes very thick with age, a calcareous 
deposit obliterating all the markings. The horny connecting 
tubes between the cells are unusually long. 
2.—CoTHURNICELLA, 0. g. 
Cells in simple rows, each row arising from the side of a joint of an arti- 
culated 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 moveable operculum. Ovicell an ordinary 
cell of a series, much enlarged, but scarcely modified in fori. 
C. dedala, un. sp. 
The only known species. 
This genus seems to have a sufficient number of characters 
in common with Catenicella to warrant its admission into 
the same family. It is, however, at once distinguished from 
the rest of the Catenicellide by its simple rows of cells 
arising regularly from the joints of an articulated stem. The 
joimts 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. dedala 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 
triangular space within the fork is closely strung, like a harp, 
with parallel strings of cells. The anterior aspect of the 
cellis 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 
