- a ring or saddle-shaped region of glandular tissue in the body wall of certain annelids, as earthworms and some leeches, that after copulation secretes a cocoon in which the eggs and sperm are deposited for fertilization and development.
- a thickened saddle-like region of epidermis in earthworms and leeches whose secretions bind copulating worms together and later form a cocoon around the eggs
