These Halloween bones offer a lesson in fretboard anatomy. Cutting away all the sharps and flats (the black keys) leaves only the natural notes (the bones). The "head" of each octave is a C (a skull), and going up the scale there are only two places where the bones connect: the E bone's connected to the F bone, and the B bone's connected to the C bone, but that's all (now hear the word of the Lord!). There are just three bones at the first fret (you know their names), but no bones at the eleventh (just sharps and flats) so all the notes from the 12th fret up are in their own separate skeleton.
The skeleton music in this month's sightreading handout* was written in 1874 and introduced the xylophone to sound like bones. It's theme was the legend that, on Halloween night, the devil would summon skeletons from their graves to dance wildly until dawn. If you've seen the Fantasia rendition, then you get the right visual image but with the wrong music (that one was Mussorgsky's Night on Bald Mountain). But this month's sightread is by a French composer, which might be the only reason that, despite it's morbid theme, this piece was included in the opening ceremonies for this summer's Olympics in Paris. Really! See the youtube link on the back page.
The actual title of this month's music is much, much older; it's taken from a meme in European art that goes back to the Middle Ages and perhaps all the way to the Black Death, and it explains why the skeletons are laughing. No, it's not the Dies Irae, though our composer also included that theme in his full version.
One last hint: the music begins with alternating tritones, because that interval was long known as the diabolus in musica or the "Devil in music". And still they put all this in the Olympics! Puzzled? Click on the pdf and see for yourself.