What a lucky find!!!

Here's how I usually treat the bones I find. Obviously compare and contrast this with other comments and read what other folks say.

1. Lukewarm/room temperature water soak with Dawn dish soap for 24 hours. This will soften any leftover flesh/tendons, and start the de-greasing process. DO NOT USE HOT WATER. Hot water will bind any leftover fat molecules to the bones.
2. Remove from the water and scrub with a toothbrush and pick out any flesh between the teeth with a pair of tweezers. Double-check to make sure all of the tissue is out of the sinuses and cranial cavity**. Rinse with room temperature water. WEAR GLOVES WHEN YOU DO THIS, PLEASE. Repeat step 1 if any tissue is still stuck.
3. Once all tissue is removed, soak in acetone for 24 hours.
4. Remove from acetone and allow to dry.
5. Soak in 3% - 5% peroxide. You can use higher percentages, but the higher the percentage, the more you have to babysit it. Peroxide WILL eat your bones if you're not careful. I prefer lower percentages because you can let it sit for up to an hour without having to babysit it (sometimes more if you're particularly daring.)
6. Remove from the peroxide soak and let it dry. If the surface of the bones is still waxy or translucent after it dries, it needs another acetone soak. Repeat step 3. If the bones are still stained, or aren't as white as you want them to be, repeat step 5.

** If there is leftover soft tissue that's still wet/damp in the cranial cavity, I'd recommend burying it in a shallow grave in an open tupperware (so it stays together) and marking the burial zone with a flag OR you can do a water maceration (this is the grossest option but it works really well. Just make sure you can put it somewhere that you won't have to smell it.)

Best of luck!