There are sometimes a few fine ribs on the posterior end of the shell.

Water is drawn into the shell mainly at the posterior end.

The posterior end of the female body stays outside the root.

The posterior end of the foot in this species can act as a sucker.

Many species have a pair of short projections at the posterior end.

The female also has a pointed posterior end with a long or short tail.

The posterior end lifts out of the water and forms a right angle.

In the winter, most individuals have a long spine at the posterior end.

The scales are mostly present on the posterior end of the body.