Chromophil cells in earthworms are found in the........

In Earthworm,the arrangement of blood vessels is:

What is the function of the clitellum in $Pheretima$?

Which of the following animal's sensory system does not have eyes but does possess light and touch sensitive organs (receptor cells) to distinguish the light intensities and to feel the vibrations in the ground?

Integumentary nephridia are also called

Define the following terms:
$(i)$ Cocoon
$(ii)$ Worm casting