176 PROCEEDINGS OF SOCIETIES. 
about a fortnight, anchored itself by a sort of byssus to the sides 
of the vessel. First, a mucous substance was deposited on the 
glass at four different points; then four sets of cords (about fifty 
in each) united these attachments, two to the long axis of the 
mouth of the case, and two to the angles of the base. The animal 
lay much shortened, with its head curved round, its legs close 
together, entirely within the case. This larval form was found 
abundantly in December instant, in bog pools, on the west side 
of Carrick Mountain, near Wicklow. 
Dr. Moore showed the hairs of Isonandra gutta (gutta-percha 
plant), and drew attention to their structure. 
The Rey. E. O’Meara exhibited several new species of Dia- 
tomaceze, descriptions and figures of which are intended to appear 
in this Journal; these he respectively named Cocconeis clavigera, 
Rhaphoneis suborbicularis, R. hispida, and R. Jonesii. 
- Mr. Archer drew attention to, and exhibited specimens of, a 
minute unicellular chlorophyllaceous plant, certainly one he had 
never seen before; and, though great diversity showed itself as 
regards the individual cells, they had all a common character, so 
that at a glance they might be recognised as one and the same 
thing. 
Viewed so far as regards outward form only, this plant might 
be regarded as falling under Nageli’s genus Polyedrium; but it 
differs so greatly therefrom in its mode of growth that it could 
not be referred at all to that genus. It forms polyhedral cells of 
varying sizes, and of the most varied number of angles, sometimes 
even subrotund and cornute. In all the specimens each angle or 
extension seemed to be terminated in a kind of knob-like, hyaline 
tubercle—as it were a kind of thickening of the cell-wall; and by 
certain of these tubercles the cells often mutually cohered to 
the number of two, three, or four together. 
Tt will thus be seen that the external form points to the genus 
Polyedrium, with no described speeies of which it could, however, 
be at all confounded, even thus only externally viewed. 
But in Polyedrium the mode of increase is by a brood of small 
young Polyedria, indefinite in number, being formed by a break- 
ing up of the entire cell-contents of the parent Polyedrium. These 
escape by the bursting of the parent cell-wall, and seem by de- 
grees to assume the form of the parent. 
In the present plant, on the other hand, the cells increase by 
transverse division—one old cell into two—and they often cohere 
by a kind of fusion at the knob-like extremities of certain of the 
prominences, reminding us somewhat of the indeed still more 
regular manner in which the frustules of Diatoma, for instance, 
hang on together. 
Now, this must necessarily place this plant away from Polye- 
drium. Pending a knowledge of the genus Trochiscia (Kiitz.), it 
