In $Pheretima$, the number of ring vessels per segment in $12^{\text{th}}$ and $13^{\text{th}}$ segments is: (in $pairs$)

Identify the incorrect statements among the following:
$(a)$ In earthworm,a single male genital pore is present.
$(b)$ Setae help in locomotion of earthworm.
$(c)$ The muscular layer in the body wall of earthworm is made up of only circular muscles.
$(d)$ Typhlosole is a part of the intestine of earthworm.

Which of the following statements is incorrect regarding the anatomy of an earthworm?

Give a scientific reason: The blood vascular system of leeches is also called the haemocoelomic system.

How many types of nephridia are present in earthworm?

Which of the following types of nephridia is not found in earthworms?