ClipArt ETC
"Vertical section of a fresh-water sponge (Spongilla), showing the arrangement of the canal-system. C, ciliated chambers; DP, dermal pores; Ex, excurrent canals; GO, openings of the excurrent canals; PG, paragastric cavity; SD, subdermal cavities; O, osculum." -Parker, 1900

Spongilla

"Vertical section of a fresh-water sponge (Spongilla), showing the arrangement of the canal-system.…

"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…