Distinguish between the following
(a) Prostomium and peristomium
(b) Septal nephridium and pharyngeal nephridium
| Prostomium | Peristomium |
| Prostomium is a dorsal lobe which is present on the ventral mouth. | Peristomium is the first segment of earthworm with a ventral mouth. |
| It overhangs the mouth of an earthworm. | It surrounds the mouth opening. |
| Septal nephridium | Pharyngeal nephridium |
| Present on both sides of inter-segmental septa. | They are present as three paired tufts in the fourth, fifth and sixth segments. |
|
| They open into the intestine. | They are closed. |