Ennealogy

These works […] appear, upon closer scrutiny, to be dramatic, and are actually the seventh and eighth parts of an “ennealogy” (as it were), perhaps “polylogy,” for dramas in Japan frequently are protracted to such lengths.

[…] George Passant, the protagonist of C.P. Snow’s second novel in the Strangers and Brothers ennealogy […]

Of course, nobody in their right mind would want to commit to an octalogy, ennealogy, or decalogy—or even more!— unless you were a fan of, say, Lemony Snicket