Flawed Logic

Let us follow the flying mud crab, says Lucius. 

If it is a flying mud crab, says Pontius.

It's heading for the shore, say Lucius. 

So it is, says Pontius. Do we want to go there?

Let's decide en route, says Lucius. Otherwise we'll lose it.

Good thinking, says Pontius.

They follow the flying mud crab.

It's not far to the shore.

Before they have decided if they want to go there, they are there

And the mud crab has landed.

Lucius and Pontius float in as near as they dare.

The mud crab is half in and half out of the water.

Looks like an ordinary mud crab, says Lucius.

A dead one, says Pontius. The question is how did it fly?

Neither of them has noticed Roo-kai's thin red legs standing nearby.

Roo-kai steps towards them.

Oystercatcher! shouts Pontius. 

Fear not, says Roo-kai. I see you have followed my crab.

Your crab, says Lucius. Are you planning to eat it?

I am, says Roo-kai, but only after I have completed my mission.

You intrigue us, says Lucius.

You do, says Pontius. What is your mission?

To lure you to shore with this crab, says Roo-kai.

To what end? asks Pontius.

To this end, says Roo-kai. Gaius Plinius Secundus wishes to speak with you.

A fellow Gondwanian? says Lucius.

I don't know about that, says Roo-kai. He's always claimed to be an ancient Roman.

Gaius has ventured into the shallows, and overheard this.

I am he of whom Roo-kai speaks, says Gaius. What's this about a fellow Gondwanian? 

Your names, says Pontius. 

They are Roman names, says Gaius. A praenomen, nomen and cognomen. 

We make do with Lucius and Pontius, says Lucius. And have done so for ever.

This is most interesting, says Gaius. So you believe you have lived in Macquarie Harbout for ever?

If our memory serves us, says Pontius.

Because, says Gaius, it is currently thought that the life span of a maugean skate is fifteen at the most.

Eons? asks Lucius.

Years, says Gaius.

Ho ho! says Pontius. 

What is your side of the story? asks Gaius.

We come from a time when fish had no bones, says Lucius. And we still have no bones  Ergo...

That is flawed logic, says Gaius.