Harry Potter and the Sorcerer's Stone

I know there are a lot of decriers of the HP series out there, but I am continually amazed (at least in the earlier books) at how many literary allusions Rowling is able to entertain.  As I was explaining to a recent class about allusions, it typically doesn't hurt if you miss the reference to your overall understanding of a work, but if you do happen to catch it, it's kind of a wink you can share with the author, a sense of being "in the know."

In the last two days, I've come across two more that had previously "alluded" (HAR!) me.  Sagetrieb brought up "Septimus" in Woolf's work.  Isn't there a character named Septimus in HP?

Where else do you find allusions? 

The only Septimus I can think of is Septimus Weasley, father of Arthur Weasley.  I'm not quite sure the significance of his name though his character is important as background information.  Apparently he had married Cedrella Black (of the Black family - an aunt of Sirius?)  Similar to Sirius, Cedrella was removed from the Black Family tree because she was seen as a traitor.