cli·tel·lum 
(klī-tĕləm)
(klī-tĕləm)n. pl. cli·tel·la (-tĕlə)
A glandular swelling of the epidermis of certain annelid worms, such as earthworms, that secretes a viscous fluid to form a cocoon in which the eggs are deposited.
[New Latin clītellum, sing. of Latin clītellae, packsaddle; see klei- in the Appendix of Indo-European roots.]
clitellumof an earthworm