A new species of Coelastrum 237 
the members of one tier alternating with those of the other; some¬ 
times, however, the appearance is of five cells in one plane with one 
cell above and two cells below (Fig. xn). 
The cells of the coenobia cohere by means of broad flattened 
surfaces and there are no connecting rods or tubercles. 
The peculiarity of this organism is the splitting off of little cap- 
like structures from the. free surfaces of the cells. First of all 
minute pads appear, about one-fifth or one-sixth of the circumference 
apart (Fig. iv); then fission of the outer layer of the cell-wall seems to 
occur along a line connecting at least two of these pads, and a little 
circular or four-cornered cap is detached (Figs, xi, xn and xm). An 
eight-celled colony with the little caps well defined presents a very 
characteristic appearance. Sometimes fission of the wall occurs along 
the surface attached to other cells; in this case, of course, the cell 
in question ultimately breaks away and the cap-shaped structure is 
left adhering to the residue of the main colony like a little saucer 
(Figs, vii and vm). 
The small pads may correspond to the special short truncate 
processes or warts that unite the cells in other species of Coelastrum, 
e.g. C. Morns W. and G. S. West, C. scabrum Reinsch, C. cambricum 
Archer, and C. reticulatum Danz. It may be the case that the cell- 
wall is becoming more mucilaginous at these spots, and that this 
causes splitting off of the caps. It is possible that the caps themselves 
ultimately become mucilaginous and merge into the mucilaginous 
envelope, as is indicated in Fig. x where folds in the investment seem 
to pass over into the little caps. 
With regard to multiplication, the formation of auto-colonies by 
the cells of an entire colony has not been observed. Cases, however, 
like that shown in Fig. xiv would seem to indicate the possibility of 
formation of daughter colonies by single cells which may have been 
produced by disintegration of adult coenobia, the daughter-colony 
being at first enclosed within the mucilaginous wall of the parent cell. 
The stalk-like protuberance of the investment in Fig. xiv may have 
resulted from the gelatinisation of one of the incipient caps. 
The following Latin diagnosis is appended: 
Coelastrum schizodermaticum n.sp. 
C. coenobiis globosis, tegumento mucoso interdum praeditis, e 
cellulis sphaericis vel subangularibus confertis, vulgo 8, constantibus, 
faciebus deplanatis cohaerentibus, membrana lamellata; lacunis inter 
