Solution

(i) Nephridia are segmentally arranged excretory organs present in earthworms.
(ii) On the basis of their location, three types of nephridia are found in earthworms. They are :
(a) Septal nephridia : These are present on both sides of the intersegmental septa behind the 15$$^t$$^h$$ segment and they open into the intestine.
(b) Integumentary nephridia : These lie attached to the body wall from the third segment to the last segment, which opens on the body surface.
(c) Pharyngeal nephridia : These are present as three paired tufts in fourth, fifth, and sixth segments.