hard sponge,—the horny kind (common bathing sponge),—which, when alive, has the interstices filled with these Amoeba-like bodies. Some of the descendants of the Horny Sponges were metamorphosed into the flinty kind, to which our fresh-water sponge belongs, and the Venus's flowerbasket (Euplectella), whose framework rivals in delicacy the most beautiful lace. From the flinty kind were derived most likely the Pitcher Sponges, in which the framework takes the form of a goblet or pitcher. These are often beautifully preserved in a fossil state (Ventriculites, Guettardia); they are nearly allied in their structure to Corals and Anemones. Still closer to the Corals are the calcareous sponges in their affinities. The natural history of Sponges, to those to whom it is known best, is full of evidences in favor of the theory of Evolution.
TREE II.
Actinozoa. Hydrozoa. Anemones. Corals. Jelly-Fish, Calcareous. Pitcher. Gummy^ Flinty. Horny. Slimy. Hard Sponges. Soft Sponges. Original Sponge. Amoeba. Monas.
