from the GNU version of the Collaborative International Dictionary of English
- n. A genus of siliceous sponges found in fresh water.
from The Century Dictionary and Cyclopedia
- n. The only genus of fresh-water sponges, belonging to the group Fibrospongiæ.
Sorry, no etymologies found.
Both chemical and histological observations showed the abundant presence of starch in the green cells, and thus these planarians, and presumably also _Hydra spongilla_, etc., were proved to be truly "vegetating animals."