Sentence:  She was a fat, round little woman, richly apparelled in velvet and lace, […]; and the way she laughed, cackling like a hen, the way she talked to the waiters and the maid, […]&mdash;all these unexpected phenomena impelled one to <WSD>hysterical</WSD> mirth, and made one class her with such immortally ludicrous types as Ally Sloper, the Widow Twankey, or Miss Moucher. 
Meaning of the word marked with <WSD> tags:  Provoking uncontrollable laughter.