What would you call the literary device being used in this witty description I came across while reading Tom Jones? Somehow 'sarcasm' and 'irony' don't seem appropriate, yet it's definitely a case of meaning something very different from what the words literally say.

He now lived, for the most part, retired in the country, with one sister, for whom he had a very tender affection. This lady was now somewhat past the age of thirty, an aera at which, in the opinion of the malicious, the title of old maid may with no impropriety be assumed. She was of that species of women whom you commend rather for good qualities than beauty, and who are generally called, by their own sex, very good sort of women--as good a sort of woman, madam, as you would wish to know. Indeed, she was so far from regretting want of beauty, that she never mentioned that perfection, if it can be called one, without contempt; and would often thank God she was not as handsome as Miss Such-a-one, whom perhaps beauty had led into errors which she might have otherwise avoided. Miss Bridget Allworthy (for that was the name of this lady) very rightly conceived the charms of person in a woman to be no better than snares for herself, as well as for others; and yet so discreet was she in her conduct, that her prudence was as much on the guard as if she had all the snares to apprehend which were ever laid for her whole sex. Indeed, I have observed, though it may seem unaccountable to the reader, that this guard of prudence, like the trained bands, is always readiest to go on duty where there is the least danger. It often basely and cowardly deserts those paragons for whom the men are all wishing, sighing, dying, and spreading, every net in their power; and constantly attends at the heels of that higher order of women for whom the other sex have a more distant and awful respect, and whom (from despair, I suppose, of success) they never venture to attack.

I say it's irony of the highest order. What makes you think otherwise?

Arnie, I told Shu that it was the British form of "irony." Remember, we differ on that definition.

Henry Fielding was a master of irony, and Tom Jones contains some of the finest examples of irony in the English language.