Cells dividing in three planes, approximately perpendicular to each other, resulting in cuboidal to more or less spherical colonies; cells more or less angular, with membranaceous walls; all cells in the colony at maturity producing resting spores by thickening on the inside of the original separating walls, the spores being liberated by the dissolution of the colonial wall.
Type species, Endospora rubra.
The genus possesses a combination of characters not found in and other genus of the Chroococcaceae. The combination seems sufficient for generic distinction. I am therefore proposing the above diagnosis under the term Endospora to take care of several collections whose characters would not permit their being placed elsewhere. The new genus has some features which remind one of the genus Pleurocapsa, as it does likewise some members of the genus Chroococcus, but neither of these genera produces, so far as is known, endogenous resting spores by the secretion of a special wall around the whole protoplast of each cell in the colony, and in neither is there such a definite membranaceous wall separating the protoplasts. Another method of reproduction would have to be added to the Chamaesiphonaceous genus Pleurocapsa in addition to its schizogenous method of producing gonidia, and likewise the Chroococcaceous genus Chroococcus would have to be emended to incluude such forms producing specialized resting cells. It resembles the typical species in the genus Anacijstis in having a definite life cycle, at the end of which all of the cells of the colony are simultaneously changed into resting spores, the so-called rejuvenescent period. It differs from Anacystis in that the cell walls are membranaceous and adhere by their entire surface until maturity, instead of- being cartilaginous, mucilaginous, or gelatinous, as in Anacystis, such walls expanding more or less and permitting the protoplasts to migrate from each other to variable and considerable distances.