I just discovered (or had read it before, but without registering it) that Wilson's inspiration for "amphisbaenic" might have derived from Alexander Pope's Dunciad: ( a new problem now for the Kinbote/Wilson hunch!)
The lines in question are: "Thus Amphisbaena (I have read)
                            At either end assails;
                                      None knows which leads, or which is led,
                           For both Heads are but Tails."
 

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