Squirters--Affinity with Bivalves--Test--Gill-sac--Branchial
Cilia--Heart--Blood Circulation--Digestion--Tentacles--Eyes--
_Cynthia_--Currant Squirter--Four-angled Squirter--Discharge of
Eggs--Transformations--Compound Forms--_Botrylli_--Oceanic
Forms--_Pyrosoma_--Its Luminosity--Sponges--Their Habitats--
Various Species described with the Forms of their Spicula--
Motives for Study--A Protest against prevalent Errors, 298-327