I love that quotation (and other choice ones you can find by looking up
Austen
in Alan Gribben's _Mark Twain's Library:  A Reconstruction_).  But I've
always
wondered why he had such a violent reaction.  Was it just to tweak Howells,
who was a big Janeophile?  Or was it something else he was reacting to?  It
seems to me that he should have appreciated Austen's tone, satire, and
irony.
He was evidently an appreciative and insighful reader of Browning, for
example.  So why this strong distaste for Austen?  Any ideas?