The five pairs of gill slits are tiny and uniform.

The five pairs of gill slits are small, with the fourth and fifth very close together.

The five pairs of gill slits are short and curved.

There are six pairs of long gill slits, with the first pair meeting over the throat.

The five pairs of gill slits are very small and vertical.

There are five pairs of gill slits, with the first pair longer than the others.

The five pairs of gill slits are located fairly high on the body.

The five pairs of gill slits are short and nearly vertical.

The five pairs of gill slits are large, and increase in size from the first to the last.

The five pairs of gill slits are medium in length.