Synonyms for shellback

Skinner, you don't suppose Matt's like every other shellback of a skipper?

"There's never a flat foot nor a shellback but will tell you same thing, messmate," agreed Ferral heartily.

I s'pose she thought mebbe Parsonsbridge butter would churn easier than Shellback; I dono.

And there are barrels of it in this town, Mr. Shellback Holmes, waiting to be converted into song.

The word was no sooner spoken than our shellback again excelled himself.