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Sycon gelatinosum, a sponge.

Sycon Gelatinosum

Sycon gelatinosum, a sponge.

"Transverse section through the wall of a cylinder (parallel with the course of the canals), showing one incurrent canal (IC), and one radial (R) throughout their length; sp, triradiate spicules; sp', oxeote spicules of dermal cortex (dc); sp'', tetraradiate spicules of gastral cortex (gc); ec, ectoderm; en, endoderm; pm, pore membrane; pp, prosopyles; ap, apopyle; di, diaphragm; exc, excurrent passage; PG, paragastric cavity; em, early embryo; em, late embryo. The arrows indicate the course of the water through the sponge." -Parker, 1900

Sycon Gelatinosum

"Transverse section through the wall of a cylinder (parallel with the course of the canals), showing…